Recording Ink, Ink Catridge, Ink Record, Inkjet Recording Apparatus, and Inkjet Recording Method

ABSTRACT

The recording ink having a water, a water-soluble organic solvent, a colorant, and at least one fluorochemical surfactant selected from the following Structural Formulae (1) to (3). Structural Formula (1): where, Rf is a fluorine-containing group; and m, n, and p are integers in the Structural Formula (1). Structural Formula (2): where, Rf is a fluorine-containing group; X is a cationic group; Y is an anionic group; and q is an integer in the Structural Formula (2). Structural Formula (3): where, Rf is a fluorine-containing group; X is a cationic group; Y is an anionic group; and q is an integer in the Structural Formula (3).

TECHNICAL FIELD

The present invention relates to a recording ink and an ink cartridge,ink record, an inkjet recording apparatus, and an inkjet recordingmethod using the recording ink.

The present invention also relates to an inkjet recording apparatus andan inkjet recording method that realize highly reliable print recordingby preventing reduction in ink repellency caused by the elution ofsilicone resin from the ink repellent is layer of a nozzle head anddeterioration in discharge stability caused by changes in the nozzleshape.

BACKGROUND ART

Conventionally, an inkjet recording apparatus mainly uses aqueous inkusing water-soluble dyes as colorants. However, the dye ink hasdisadvantages such as poor weather-resistance and poor water-resistance.

Recently, much research has focused on pigment ink that uses pigments inplace of water-soluble dyes, and some pigment ink is commerciallyavailable. However, pigment ink still has many problems with colordevelopment and stability in comparison with dye ink. Particularly,according to technical improvement in OA printers for higher imagequality, pigment ink is required to have print quality, hue, colorsaturation, gloss, and storage stability equal to dye ink on regularpapers.

For example, inkjet printing ink is proposed as a low surface tensionaqueous pigment ink having a stable ink discharge and improved inkwettability, in which a water-soluble organic solvent, colorants, water,and perfluoroalkylsulfonate are added (see Patent Literature 1). Avariety of other ink compositions using fluorochemical surfactants havealso been proposed (see Patent Literatures 2, 3, and 4).

However, these proposed compositions all have problems such as poorpigment dispersion stability and poor fixing properties and colordevelopment on recording media when the colorants are pigments.Generally, in low surface tension aqueous ink having improved inkwettability, the ink has high foaming properties and easily foams underthe influence of surfactants used in the ink, which adversely affectsthe filling and stable discharge of the ink.

As for color development, C.I. Pigment Red 122 and C.I. Pigment Blue15:3 are generally used for the pigment ink in magenta and cyan colors,respectively, and have different color reproduction ranges in comparisonwith dye ink. Toning is used to reduce hue errors. However, reduction incolor saturation is inevitable and problems with print quality occur insuch a case.

On the other hand, pigments themselves have been modified to changetheir hue without toning. For example, cyan pigments having hue in thesame range as cyan dyes have been proposed in Patent Literature 5 wherephthalocyanine pigment having a specific crystalline structure is used.However, they do not satisfy all properties including the problem ofcost.

On the other hand, many inkjet recording inks have been proposed inwhich an ink set comprising pigments as black ink materials and dyes asyellow, magenta, and cyan color ink materials is used (see PatentLiterature 6). However, in these proposals, sufficient regular paperproperties in printing on regular paper have not been achieved.

According to technical improvements in OA printers for higher imagequality, there is an increasing demand in relation to quality, hue,color saturation, and gloss. Particularly, there is an increasing demandfor image quality with regard to pigment ink.

Subsequently, a technique is proposed in which a fluorochemicalsurfactant is contained in the pigment ink to improve wettability onpaper, thereby improving color development (see Patent Literature 7). Anattempt is made to use silicone resin as the ink repellent layer of anozzle head in order to use a fluorochemical surfactant-containingpigment ink having improved wettability.

These proposed techniques allow for improvement in color development ofthe pigment ink. However, the silicone resin layer as the ink repellentlayer of a nozzle head problematically deteriorates as a result of theelution of its components after it makes contact with the fluorochemicalsurfactant containing ink.

Therefore, the silicone resin layer is made thicker to ensure inkrepellency even after the components elute from the silicone resin layerof the nozzle head to a certain extent. However, sufficient achievementhas not been observed. When the silicone resin layer of the nozzle headis made thicker, it becomes difficult to produce nozzle heads withuniform quality, and it is still difficult to sufficiently function as anozzle surface (such as stable discharge and cleaning ability).

Hence, there is a high demand for the early providing of a recording inkhaving improved color development properties ensuring highly stabledischarge and excellently uniform solid image parts, and consequently,improved color saturation to form high quality images and, an inkcartridge, ink record, an inkjet recording apparatus, and an inkjetrecording method, all using the recording ink.

Patent Literature 1 Japanese Patent Application Laid-Open (JP-A) No.57-90070

Patent Literature 2 Japanese Patent Application Laid-Open (JP-A) No.4-211478

Patent Literature 3 Japanese Patent Application Laid-Open (JP-A) No.5-230409

Patent Literature 4 Japanese Patent Application Laid-Open (JP-A) No.6-200200

Patent Literature 5 Japanese Patent Application Laid-Open (JP-A) No.2000-17207

Patent Literature 6 Japanese Patent Application Laid-Open (JP-A) No.2000-239590

Patent Literature 7 Japanese Patent Application Laid-Open (JP-A) No.2003-335987

DISCLOSURE OF INVENTION

The first purpose of the present invention is to provide a recording inkhaving improved color development properties ensuring highly stabledischarge and excellently uniform solid image parts, and consequently,improved color saturation to form high quality images and, an inkcartridge, ink record, an inkjet recording apparatus, and an inkjetrecording method, all using the recording ink.

The second purpose of the present invention is to provide an inkjetrecording apparatus and an inkjet recording method using afluorochemical surfactant-containing ink having improved colordevelopment in which reduction in ink repellency caused by the elutionof silicone resin from the ink repellent layer of the nozzle head isprevented and deterioration in discharge stability caused by changes inthe nozzle shape is suppressed, thereby realizing highly reliable printrecording.

The recording ink of the present invention contains at least water, awater-soluble organic solvent, a colorant, and at least onefluorochemical surfactant selected from the following StructuralFormulae (1) to (3).

where, Rf is a fluorine-containing group; and m, n, and p are integersin the Structural Formula (1).

where, Rf is a fluorine-containing group; X is a cationic group; Y is ananionic group; and q is an integer in the Structural Formula (2).

where, Rf is a fluorine-containing group; X is a cationic group; Y is ananionic group; and q is an integer in the Structural Formula (3).

According to the recording ink of the present invention, an ink using anaqueous dispersion of polymer fine-particles containing color materials(coloring fine-particles) as a colorant, a water-soluble organicsolvent, and a fluorochemical surfactant having a specific chemicalstructure selected from the Structural Formulae (1) to (3) above ischaracterized by the fact that the ink has a lower surface tension thanthe prior art ink in spite of a higher viscosity and, therefore, thevehicle rapidly infiltrates into regular papers and the color materialcomponents easily remain on the surface during printing. In addition,using the fluorochemical surfactant prevents the color materials frombeing unevenly distributed, encouraging them to evenly appear on thepaper surface and, further, remarkably improving the dye-affinity to thepaper. Consequently, highly saturated and intensely developed imageshaving less strike-through can be obtained. Using an ink set comprisinga black ink and color inks in which the color inks contains pigment inksas color material in the ink having the coloringfine-particles-containing structure and the black ink contains aself-dispersible carbon black as a color material and has a highviscosity/a low surface tension similarly to the color inks, highquality images having high black concentrations, little run at theblack-color borders, remarkably improved color saturation resulting fromthe fluorochemical surfactant having a specific structure, and lessstrike-through for double face printing can be obtained.

It is preferable in the recording ink of the present invention that Rfin the above Structural Formulae (1) to (3) be the perfluoroalkyl groupand that the fluorochemical surfactant be at least one selected from thefollowing Structural Formulae (1-1) to (3-1).

where, Rf is CF₃ or CF₂CF₃; and n is 1 to 4, m is 6 to 25, and p is 1 to4.

where, Rf is CF₃ or CF₂CF₃; and q is 1 to 6.

where, Rf is CF₃ or CF₂CF₃; and q is 1 to 6.

It is preferable in the recording ink of the present invention that thecontent of at least one fluorochemical surfactant selected from theStructural Formulae (1) to (3) be 0.01% by mass to 10% by mass, that thecolorant be at least one of pigments, dyes, and coloring fine-particles,the pigment has at least one hydrophilic group on the surface, is atleast one of water-dispersible and water-soluble in the absence ofdispersant, that the water-soluble organic solvent is at least oneselected from glycerin, ethylene glycol, diethylene glycol, triethyleneglycol, propylene glycol, dipropylene glycol, tripropylene glycol,1,3-butanediol, 2,3-butanediol, 1,4-butanediol, 3-methyl-1,3-butanediol,1,5-pentanediol, tetraethylene glycol, 1,6-hexanediol,2-methyl-2,4-pentanediol, polyethylene glycol, 1,2,4-butanetriol,1,2,6-hexanetriol, thiodiglycol, 2-pyrrolidone, N-methyl-2-pyrrolidoneand N-hydroxyethyl-2-pyrrolidone, and at least one selected from cyanink, magenta ink, yellow ink, and black ink.

The ink cartridge of the present invention comprises a containercontaining the recording ink of the present invention. The ink cartridgeof the present invention is preferably used in inkjet recording systemprinters. By recording with the ink contained in the ink cartridge,improved color development, highly stable discharge, and excellentlyuniform solid image parts are achieved, thereby forming high qualityimages.

The first embodiment of the inkjet recording apparatus of the presentinvention at least comprises an ink drops discharging unit configured todischarge the recording ink drops to form an image by applying impulseto the recording ink

The same head of the ink drops discharging unit is used for dye ink andpigment ink that are appropriately switched.

In the first embodiment of the inkjet recording apparatus, the ink dropsdischarging unit configured to discharge the recording ink drops to forman image by applying impulse to the recording ink. Consequently,improved color development, highly stable discharge, and excellentlyuniform solid image parts are achieved, thereby forming high qualityimages.

It is preferable in the first embodiment of the inkjet recordingapparatus of the present invention that the impulse be at least oneselected from heat, pressure, vibration, and light.

The second embodiment of the inkjet recording apparatus of the presentinvention at least comprises an ink drops discharging unit configured todischarge the recording ink drops to form an image by applying theimpulse to the recording ink. The ink drops discharging unit comprises anozzle head portion having a silicone resin-containing ink repellentlayer on the ink discharging surface. The ink used in this inkjetrecording apparatus contains at least water, a colorant, afluorochemical surfactant, and an aminopropanediol compound.

In the second embodiment of the inkjet recording apparatus, reduction inink repellency caused by elution of silicone resin from the inkrepellent layer of the nozzle head is prevented and deterioration indischarge stability caused by changes in the nozzle shape is suppressed,thereby highly reliable print recording can be realized.

It is preferable in the second embodiment of the inkjet apparatus thatthe aminopropanediol compound is 2-amino-2-ethyl-1,3-propanediol, thecontent of the aminopropanediol compound in the ink is 0.01% by mass to10% by mass, and the fluorochemical surfactant is at least one selectedfrom the following Structural Formulae (A), (1), (2) and (3).CF₃CF₂(CF₂CF₂)_(j)—CH₂CH₂—O—(CH₂CH₂O)_(k)H  Structural Formula (A)

where, j and k are integers in the Structural Formula (A).

where, Rf is a fluorine-containing group; and m, n, and p are integersin the Structural Formula (1).

where, Rf is a fluorine-containing group; X is a cationic group; Y is ananionic group; and q is an integer in the Structural Formula (2).

where, Rf is a fluorine-containing group; X is a cationic group; Y is ananionic group; and q is an integer in the Structural Formula (3).

It is preferable in the second embodiment of the inkjet apparatus thatthe content of the fluorochemical surfactant in the ink be 0.05% by massto 20% by mass, that the colorant be at least one of pigments, dyes, andcoloring fine-particles, that the pigment has at least one hydrophilicgroup on the surface and be at least one of water-dispersible andwater-soluble in the absence of dispersant, and that the impulse be oneselected from heat, pressure, vibration, and light.

The first embodiment of the inkjet recording method of the presentinvention at least comprises an ink drops discharging unit configured todischarge the recording ink drops to form an image by applying theimpulse to the recording ink of the present invention. Using the firstembodiment of the inkjet recording method, improved color development,highly stable discharge, and excellently uniform solid image parts areachieved, thereby high quality images can be formed.

It is preferable in the first embodiment of the inkjet recording methodof the present invention that the impulse be at least one selected fromheat, pressure, vibration, and light.

The second embodiment of the inkjet recording method of the presentinvention at least comprises an ink drops discharging unit configured todischarge the recording ink drops to form an image by applying impulseto the recording ink. The ink drops discharging step is performed usinga nozzle head having a silicone resin-containing ink repellent layer onthe ink discharging surface. The ink used in the inkjet recording methodcontains at least water, a colorant, a fluorochemical surfactant, and anaminopropanediol compound.

Using the second embodiment of the inkjet recording method, reduction inink repellency caused by elution of silicone resin from the inkrepellent layer of the nozzle head is prevented and deterioration indischarge stability caused by changes in the nozzle shape is suppressed,thereby realizing highly reliable print recording.

It is preferable in the second embodiment of the inkjet recording methodthat the aminopropanediol compound be 2-amino-2-ethyl-1,3-propaneddiol,that the fluorochemical surfactant be at least one selected from thefollowing Structural Formulae (A), (1), (2) and (3), and that theimpulse be at least one selected from heat, pressure, vibration, andlight.CF₃CF₂(CF₂CF₂)_(j)—CH₂CH₂—O(CH₂CH₂O)_(k)H  Structural Formula (A)

where, j and k are integers in the Structural Formula (A).

where, Rf is a fluorine-containing group; and m, n, and p are integersin the Structural Formula (1).

where, Rf is a fluorine-containing group; X is a cationic group; Y is ananionic group; and q is an integer in the Structural Formula (2).

where, Rf is a fluorine-containing group; X is a cationic group; Y is ananionic group; and q is an integer in the Structural Formula (3).

The ink record of the present invention comprises images formed usingthe recording ink of the present invention. In the inkjet record,improved color development, highly stable discharge, and excellentlyuniform solid image parts are achieved, by which high quality images canbe retained on the recording media.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 is a schematic illustration an example of the ink cartridge ofthe present invention.

FIG. 2 is a schematic illustration showing an example of the inkcartridge of FIG. 1 including a case (exterior).

FIG. 3 is a perspective view of an example of the ink cartridge mountingpart of an inkjet recording apparatus when the cover is opened forexplanation.

FIG. 4 is a schematic illustration showing an example of the entirestructure of an inkjet recording apparatus.

FIG. 5 is a schematic enlarged view showing an example of the inkjethead of the present invention.

FIG. 6 is an enlarged view of the components showing an example of theinkjet head of the present invention.

FIG. 7 is an enlarged cross-sectional view of the components showing anexample of the inkjet head of the present invention.

BEST MODE FOR CARRYING OUT THE INVENTION

(Recording Ink)

The recording ink of the present invention contains at least water, awater-soluble organic solvent, a colorant, and a fluorochemicalsurfactant having a specific chemical structure and, where necessary,further contains other components.

The fluorochemical surfactant having a specific chemical structure is atleast one selected from the following Structural Formulae (1) to (3).

In the Structural Formula (1), Rf is a fluorine-containing group and, inparticular, preferably a perfluoroalykyl group.

The perfluoroalkyl group is preferably those having a carbon number from1 to 10, more preferably from 1 to 3, such as —C_(n)F_(2n-1) (where, nis an integer of 1 to 10). Examples of the perfluoroalkyl group include—CF₃, —CF₂CF₃, —C₃F₇, and —C₄F₉. Among them, —CF₃ and —CF₂CF₃ areparticularly preferable.

m, n, and p are integers. Preferably, n is an integer of 1 to 4, m is aninteger of 6 to 25, and p is an integer of 1 to 4.

In the Structural Formula (2), Rf is a fluorine-containing group,preferably a perfluoroalkyl group as in the Structural Formula (1) suchas —CF₃, —CF₂CF₃, —C₃F₇, and —C₄F₉.

X is a cationic group such as quaternary ammonium groups; alkali metalsuch as sodium and potassium; and triethylamine and triethanolamine.Among them, quaternary ammonium groups are particularly preferable.

Y is an anionic group such as COO, SO³, SO⁴, and PO⁴.

q is an integer, for example, preferably of 1 to 6.

In the Structural Formula (3), Rf is a fluorine-containing group,preferably a perfluoroalkyl group as in the Structural Formula (1) suchas —CF₃, —CF₂CF₃, —C₃F₇, and —C₄F₉.

X is a cationic group such as quaternary ammonium groups; alkali metalsuch as sodium and potassium; and triethylamine and triethanolamine.Among these, quaternary ammonium groups are particularly preferable.

Y is an anionic group such as COO, SO₃, SO₄, and PO₄.

q is an integer, for example, preferably of 1 to 6.

At least one fluorochemical surfactant selected from the StructuralFormulae (1) to (3) above are preferably at least one selected from thefollowing Structural Formulae (1-1), (2-1), and (3-1), which areapproved for environmental safety by the US Environmental ProtectionAgency and preferable in view of safety. Among these, the fluorochemicalsurfactant having the Structural Formula (1-1) particularly contributesto excellent ink filling properties and stable discharge because of itsextremely low foaming properties.

where, Rf is CF₃ or CF₂CF₃; and n is 1 to 4, m is 6 to 25, and p is of 1to 4.

where, Rf is CF₃ or CF₂CF₃; and q is 1 to 6.

where, Rf is CF₃ or CF₂CF₃; and q is 1 to 6.

The content of at least one fluorochemical surfactant selected from theStructural Formulae (1) to (3) in the recording ink is preferably 0.01%by mass to 10% by mass, more preferably 0.1% by mass to 5% by mass. Whenthe content of the fluorochemical surfactant is lower than 0.01% bymass, improved color development may not be obtained. When it is higherthan 10% by mass, the ink may have deteriorated storage stability.

The recording ink of the present invention can contain at least onefluorochemical surfactant selected from the Structural Formulae (1) to(3) individually or in combination of two or more. Further, thefluorochemical surfactant having the Structural Formula (1), thefluorochemical surfactant having the Structural Formula (2), and thefluorochemical surfactant having the Structural Formula (3) can be usedin combination. However, other fluorochemical, nonionic, anionic,amphoteric, and acetylene glycol surfactants can be additionally used.

Examples of the anionic surfactant include alkylallyl,alkylnaphthalenesulfonate, alkylphosphate, alkylsulfate, alkylsulfonate,alkylethersulfate, alkylsulfosuccinate, alkylestersulfate,alkylbenzenesulfonate, alkyldiphenyletherdisulfonate,alkylaryletherphosphate, alkylarylethersulfate,alkylaryletherestersulfate, olefinsulfonate, alkaneolefinsulfonate,polyoxyethylenealkyletherphosphate, polyoxyethylenealkylethersulficester salt, ethercarboxylate, sulfosuccinate, α-sulfo fatty acid ester,fatty acid salt, condensates of higher fatty acid and amino acid, andnaphthenate.

Examples of the nonionic surfactant include polyoxyethylenealkylether,polyoxyethylenealkylallyether, polyoxyethylenealkylphenylether,polyoxyethylene glycol ester, polyoxyethylenefatty acid amide,polyoxyethylenefatty acid ester, polyoxyethylenepolyoxypropylene glycol,glycerin ester, sorbitan ester, sucrose ester, polyoxyethylene ether ofglycerin ester, polyoxyethylene ether of sorbitan ester, polyoxyethyleneether of sorbitol ester, fatty acid alkanol amide, amine oxide,polyoxyethylenealkylamine, glycerin fatty acid ester, sorbitan fattyacid ester, polyoxyethylenesorbitan fatty acid ester,polyoxyethylenesorbitol fatty acid ester, and alkyl(poly)glycoxide.

Examples of the amphoteric surfactant include imidazoline derivativessuch as imidazolium betaine, dimethylalkyllauryl betaine, alkylglycine,alkyldi(aminoethyl)glycine.

Examples of the acetylene glycol surfactant include acetylene glycolssuch as 2,4,7,9-tetramethyl-5-decyn-4,7-diol,3,6-dimethyl-4-octyn-3,6-diol, 3,5-dimethyl-1-hexyn-3-ol (for example,Surfynol 104, 82, 465, 485 or TG, by Air Products (the US)).

The addition rate of the surfactants can be appropriately adjusted aslong as the purpose and efficacy of the present invention is notimpaired.

—Colorant—

The colorant can be any one of pigments, dyes, and coloringfine-particles.

An aqueous dispersion of polymer fine-particles containing coloringmaterials is preferably used as the coloring fine-particles.

Here, the “containing coloring materials” means either one or both ofthe state that coloring materials are sealed in polymer fine-particlesand the state that coloring materials are adsorbed to the surface ofpolymer fine-particles. All coloring materials mixed in the recordingink of the present invention are not necessarily sealed in or adhered topolymer fine-particles. The coloring materials can be dispersed in theemulsion as long as the efficacy of the present invention is notimpaired. The coloring materials are not particularly limited and may beappropriately selected according to the purpose as long as they areinsoluble or hardly soluble in water and can be adhered to the polymer.

Here, the “insoluble or hardly soluble in water” means that 10 parts bymass or more of coloring materials are not dissolved in 100 parts bymass of water at 20° C. Further, “soluble” means that separated orprecipitated coloring materials are not visible at the surface or bottomof an aqueous solution.

The average particle diameter of the polymer fine-particles containingcoloring materials (coloring fine-particles) in the ink is preferably0.16 μm or smaller.

The content of the coloring fine-particles in the recording ink is, bysolid content, preferably 8% by mass to 20% by mass, more preferably 8%by mass to 12% by mass.

The colorant can be dyes, such as water-soluble, oil-soluble, anddisperse dyes, and pigments. Oil-soluble and disperse dyes arepreferable in view of excellent adsorption and sealable properties.However, pigments are preferably used in view of light stability ofobtained images.

The dyes are preferably dissolved in an organic solvent such as a ketonesolvent at a rate of 2 g/L or higher, more preferably at a rate of 20g/L to 600 g/L, in view of efficient impregnation into polymerfine-particles.

Water-soluble dye can be those classified as acidic, direct, basic,reactive, and food dyes in the color index and preferably has excellentwater resistance and light stability.

Examples of the acidic and food dyes include C.I. Acid Yellow 17, 23,42, 44, 79, 142; C.I. Acid Red 1, 8, 13, 14, 18, 26, 27, 35, 37, 42, 52,82, 87, 89, 92, 97, 106, 111, 114, 115, 134, 186, 249, 254, 289; C.I.Acid Blue 9, 29, 45, 92, 249; C.I. Acid Black 1, 2, 7, 24, 26, 94; C.I.Food Yellow 3, 4; C.I. Food Red 7, 9, 14; C.I. Food Black 1, 2, and thelike.

Examples of the Direct dye include C.I. Direct Yellow 1, 12, 24, 26, 33,44, 50, 86, 120, 132, 142, 144; C.I. Direct Red 1, 4, 9, 13, 17, 20, 28,31, 39, 80, 81, 83, 89, 225, 227; C.I. Direct Orange 26, 29, 62, 102;C.I. Direct Blue 1, 2, 6, 15, 22, 25, 71, 76, 79, 86, 87, 90, 98, 163,165, 199, 202; C.I. Direct Black 19, 22, 32, 38, 51, 56, 71, 74, 75, 77,154, 168, 171, and the like.

Examples of the Basic dye include C.I. Basic Yellow 1, 2, 11, 13, 14,15, 19, 21, 23, 24, 25, 28, 29, 32, 36, 40, 41, 45, 51, 53, 63, 64, 65,67, 70, 73, 77, 87, 91; C.I. Basic Red 2, 12, 13, 14, 15, 18, 22, 23,24, 27, 29, 35, 36, 38, 39, 46, 49, 51, 52, 54, 59, 68, 69, 70, 73, 78,82, 102, 104, 109, 112; C.I. Basic Blue 1, 3, 5, 7, 9, 21, 22, 26, 35,41, 45, 47, 54, 62, 65, 66, 67, 69, 75, 77, 78, 89, 92, 93, 105, 117,120, 122, 124, 129, 137, 141, 147, 155; C.I. Basic Black 2, 8, and thelike.

Examples of the reactive dye include C.I. Reactive Black 3, 4, 7, 11,12, 17; C.I. Reactive Yellow 1, 5, 11, 13, 14, 20, 21, 22, 25, 40, 47,51, 55, 65, 67; C.I. Reactive Red 1, 14, 17, 25, 26, 32, 37, 44, 46, 55,60, 66, 74, 79, 96, 97; C.I. Reactive Blue 1, 2, 7, 14, 15, 23, 32, 35,38, 41, 63, 80, 95, and the like.

The pigments are not particularly limited and may be appropriatelyselected according to the purpose. The pigments can be, for example,either inorganic or organic.

Examples of the inorganic pigments include titanium oxide, iron oxide,calcium carbonate, barium sulfate, aluminum hydroxide, barium yellow,cadmium red, chrome yellow, and carbon black. Among them, carbon blackis preferable. Examples of the carbon black include those produced byknown methods such as contact, furnace, and thermal methods, and thelike.

Examples of the organic pigments include azo pigments, polycyclicpigments, dye chelates, nitro pigments, nitroso pigments, and anilineblack. Among them, azo pigments and polycyclic pigments are preferable.Examples of the azo pigments include azo lake, insoluble azo pigments,condensed azo pigments, and chelate azo pigments. Examples of thepolycyclic pigments include phthalocyanine pigments, perylene pigments,perynone pigments, anthraquinone pigments, quinacridone pigments,dioxane pigments, indigo pigments, thioindigo pigments, isoindolinonepigments, and quinofuraron pigments. Examples of the dye chelatesinclude basic dye chelates and acidic dye chelates, and the like.

The pigments are not particularly limited in color and may beappropriately selected according to the purpose. For example, black orcolor pigments can be used. They can be used individually or incombination of two or more.

Examples of the black pigments include carbon blacks (C.I. Pigment Black7), such as furnace black, lampblack, acetylene black, and channelblack, metals such as copper, iron (C.I. Pigment Black 11), and titaniumoxide, and organic pigments such as aniline black (C.I. Pigment Black1), and the like.

Among the color pigments, examples of yellow pigments include C.I.Pigment Yellow 1 (fast yellow G), 3, 12 (disazo yellow AAA), 13, 14, 17,23, 24, 34, 35, 37, 42 (yellow iron oxide), 53, 55, 74, 81, 83 (disazoyellow HR), 95, 97, 98, 100, 101, 104, 108, 109, 110, 117, 120, 128,138, 150, and 153, and the like.

Examples of magenta pigments include C.I. Pigment Red 1, 2, 3, 5, 17, 22(brilliant fast scarlet), 23, 31, 38, 48:2 (permanent red 2B (Ba)), 48:2(permanent red 2B (Ca)), 48:3 (permanent red 2B (Sr)), 48:4 (permanentred 2B (Mn)), 49:1, 52:2, 53:1, 57:1 (brilliant carmine 6B), 60:1, 63:1,63:2, 64:1, 81 (rhodamine 6G lake), 83, 88, 92, 101 (colcothar), 104,105, 106, 108 (cadmium red), 112, 114, 122 (dimethylquinacridone), 123,146, 149, 166, 168, 170, 172, 177, 178, 179, 185, 190, 193, 209, and219, and the like.

Examples of cyan pigments include C.I. Pigment Blue 1, 2, 15 (copperphthalocyanine blue R), 15:1, 15:2, 15:3 (phthalocyanine blue G), 15:4,15:6 (phthalocyanine blue E), 16, 17:1, 56, 60, and 63, and the like.

Examples of intermediate color, red, green, and blue, pigments includeC.I. Pigment Red 177, 194, 224, C.I. Pigment Orange 43, C.I. PigmentViolet 3, 19, 23, 37, and C.I. Pigment Green 7, 36, and the like.

Among the pigments, self-dispersible color pigments that have at leastone hydrophilic group bound to the pigment surface directly or viaanother atomic group and are stably dispersed in the absence ofdispersant are preferably used. Consequently, a dispersant fordispersing the pigments, which is required in the prior art ink, isunnecessary. Among the self-dispersible color pigments, ionicself-dispersible color pigments are preferable. Anionic or cationicself-dispersible color pigments are preferable.

Examples of the anionic hydrophilic group include —COOM, —SO₃M, —PO₃HM,—PO₃M₂, —SO₂NH₂, and —SO₂NHCOR (in which M is a hydrogen atom, alkalimetal, ammonium, or organic ammonium; R is an alkyl group having 1 to 12carbon atoms, a phenyl group that may have a substituent, or a naphthylgroup that may have a substituent). Among them, color pigments having—COOM or —SO₃M bound to the surface are preferably used.

Examples of the alkali metal “M” in the hydrophilic group includelithium, sodium, and potassium. Examples of the organic ammonium includemono- or tri-methylammonium, mono- or tri-ethylammonium, and mono- ortri-methanolammonium. Among the anionic color pigments, a color pigmenthaving —COONa bound to the surface can be obtained for example byoxidizing a color pigment with sodium hypochlorite, sulfonating, orreacting diazonium salt.

The cationic hydrophilic groups are, for example, preferably quaternaryammonium groups, more preferably the following quaternary ammoniumgroups. The pigments having any of these bound to the surface arepreferable color materials.

The cationic self-dispersible carbon black having a hydrophilic groupcan be obtained for example by treating carbon black with3-amino-N-ethylpyridium bromide to bind an N-ethylpyridyl group havingthe following Structural Formula. Needless to say, the present inventionis not limited thereto.

The hydrophilic group can be bound to the carbon black surface viaanother atomic group in the present invention. Examples of the atomicgroup include an alkyl group having 1 to 12 carbon atoms, a phenyl groupthat may have a substituent, or a naphthyl group that may have asubstituent. Examples of the hydrophilic group bound to the carbon blacksurface via another atomic group include —C₂H₄COOM (in which M is analkali metal or a quaternary ammonium), -PhSO₃M (in which Ph is a phenylgroup; and M is an alkali metal or a quaternary ammonium), and —C₅H₁₀NH₃⁺. Needless to say, the present invention is not limited thereto.

Pigment dispersion using a pigment dispersant can be used in the presentinvention.

Examples of natural pigment dispersants among the pigment dispersant asthe hydrophilic polymers include plant polymers such as acacia gum,tragacanth gum, guar gum, karaya gum, locust bean gum, arabinogalactone,pectin, and quinceseed starch, seaweed polymers such as alginic acid,carrageenfan, and agar, animal polymers such as gelatin, casein,albumin, and collagen, and microorganism polymers such as xanthein gumand dextran. Examples of semi-synthetic pigment dispersant includefibrous polymers such as methylcellulose, ethylcellulose,hydroxyethylcellulose, hydroxypropylcellulose, andcarboxymethylcellulose, starch polymers such as sodium carboxymethylstarch and sodium phosphate ester starch, and seaweed polymers such assodium alginate and propylene glycol alginate ester. Examples of puresynthetic pigment dispersant include vinyl polymers such as polyvinylalcohol, polyvinylpyrrolidone, and polyvinylmethyl ether, uncrosslinkedpolyacrylamide, polyacrylic acid and alkali metal salts thereof, acrylicresin such as water-soluble styreneacrylic resin, water-solublestyrenemaleic acid resin, water-soluble vinylnaphthaleneacrylic resin,water-soluble vinylnaphthalene maleic resin, polyvinylpyrrolidone,polyvinyl alcohol, alkali metal salt of β-naphthalenesulfonic acidformarine condensate, polymers having a salt of a cationic functionalgroup such as a quaternary ammonium and an amino group on the sidechain, and natural polymer compounds such as shellac. Among them, thosehaving a carboxylic acid group such as homopolymers of acrylic acid,methacrylic acid, and styreneacrylic acid and copolymers of monomershaving other hydrophilic groups are particularly preferable polymerdispersants.

These copolymers preferably have a mass average molecular mass of 3,000to 50,000, more preferably 5,000 to 30, 000, and further preferably7,000 to 15,000.

The mixture rate by mass of pigment to dispersant is preferably 1:0.06to 1:3, more preferably 1:0.125 to 1:3.

Resin fine-particles can be used in the present invention.

The resin fine-particles are not particularly limited and may beappropriately selected according to the purpose. Preferable examples ofthe resin fine-particles include silicone modified acrylic resinobtained by polymerizing an acrylic monomer and a silane compound in thepresence of emulsifier.

The acrylic monomer is not particularly limited and may be appropriatelyselected according to the purpose. Examples of the acrylic monomerinclude acrylic ester monomers, methacrylic ester monomers, amideacrylates, carboxylic acid-containing monomers, and the like.

Examples of the acrylic ester monomers include methyl acrylate, ethylacrylate, butyl acrylate, 2-ethylhexyl acrylate, 2-hydroxyethylacrylate, acryloyl morpholine, and N,N′-dimethylaminoethylacrylate, andthe like.

Examples of the methacrylic ester monomers include methyl methacrylate,ethyl methacrylate, butyl methacrylate, 2-ethylhexyl methacrylate,2-hydroxyethyl methacrylate, N,N′-dimethylaminoethyl methacrylate, andthe like.

Examples of the amide acrylates include N-methylolacrylamide andmethoxymethylacrylamide, and the like.

Examples of the carboxylic acid-containing monomers include maleic acid,fumaric acid, itaconic acid, acrylic acid, and methacrylic acid, and thelike.

The silane compound is not particularly limited and may be appropriatelyselected according to the purpose. Examples of the silane compoundinclude tetramethoxysilane, methyltrimethoxysilane,dimethyldimethoxysilane, phenyltrimethoxysilane,diphenyldimethoxysilane, tetraethoxysilane, methyltriethoxysilane,dimethyldiethoxysilane, phenyltriethoxysilane, diphenyldiethoxysilane,hexyltrimethoxysilane, hexyltriethoxysilane, de cyltrimethoxysilane,decyltriethoxysilane, and trifluoropropyltrimethoxysilane, and the like.

Monomers generally known as silane coupling agents can be used as thesilane compound, examples of which monomers include vinyltrichlorsilane,vinyltrimethoxysilane, vinyltriethoxysilane, p-styrenetrimethoxysilane,3-methacryloxypropylmethyldimethoxysilane,3-methacryloxypropyltrimethoxysilane,3-methacryloxypropylmethyldiethoxysilane,3-methacryloxypropyltriethoxysilane, 3-acryloxypropyltrimethoxysilane,N-2(aminoethyl) 3-aminopropylmethyldimethoxysilane, N-2(aminoethyl)3-aminopropyltrimethoxysilane, N-2(aminoethyl)3-aminopropyltriethoxysilane, 3-aminopropyltrimethoxysilane,3-aminopropyltriethoxysilane,3-triethoxysilyl-N-(1,3-dimethyl-butylidene)propylamine,N-phenyl-3-aminopropyltrimethoxysilane,N-(vinylbenzyl)-2-aminoethyl-3-aminopropyltrimethoxysilane hydrochloricacid salt, 3-ureidopropyltriethoxysilane,3-chloropropyltrimethoxysilane, 3-mercaptopropylmethyldimethoxysilane,3-mercaptopropyltrimethoxysilane, bis(triethoxysilylpropyl)tetrasulfide,3-isocyanate propyltriethoxysilane, and the like.

The silane compound may contain a hydrolyzable silyl group. The“hydrolyzable silyl group” means a silyl group containing a group thatis easily hydrolyzed (hereinafter simply termed “the hydrolyzablegroup”).

Examples of the hydrolyzable group include alkoxy, mercapto, halogen,amide, acetoxy, amino, and isopropenoxy groups.

A silyl group is hydrolyzed to a silanol group. A silanol group isdehydrated and condensed to a siloxane condensate. However, it ispreferable that the hydrolyzable silyl group disappears when hydrolyzedfollowing to polymerization. If the hydrolyzable silyl group remains,the resulting ink may have deteriorated storage stability.

The emulsifier is not particularly limited and may be selectedappropriately according to the purpose. Examples of the emulsifierinclude alkylbenzenesulfonic acid and their salt, dialkylsulfosuccinicester and their salt, alkylnaphthalenesulfonic acid and their salt,alkylnaphthalenesulfonic acid salt formalin condensates, higher fattyacid salt, higher fatty acid ester sulfonic acid salt, ethylene diaminepolyoxypropylene-polyoxyethylene condensates, sorbitan fatty acid esterand their salt, aromatic and aliphatic phosphoric acid ester and theirsalt, dodecylbenzenesulfonate, dodecylsulfate, laurylsulfate,dialkylsulfosuccinate, polyoxyethylenealkylphenylethersulfate,polyoxyethynealkylpropenylphenylethersulfate,alkylphenyletherdisulfonate, polyoxyethylenealkylphosphate,polyoxyethylenealkyletheracetate, polyoxyethylenelanoline alcohol ether,polyoxyethylenelanoline fatty acid ester, laurylalcohol ethoxylate,lauryl ether sulfuric ester salt, lauryletherphosphoric ester, sorbitanfatty ester, fatty diethanolamide, naphthalenesulfonic acid formalincondensates, and the like.

Examples of the salt include sodium and ammonium.

Reactive emulsifiers having an unsaturated double bond can be used asthe emulsifier.

Examples of the reactive emulsifier include commercially availableAdekalia soap SE, NE, PP (by Asahi Denka), LATEMUL S-180 (by Kao),ELEMINOL JS-2, ELEMINOL RS-30 (by Sanyo Kasei), and Aquaron RN-20 (byDai-ichi Kogyo Seiyaku), and the like.

The resin fine-particles preferably have an average particle diameter of10 nm to 300 nm, more preferably 40 nm to 200 nm. When the averageparticle diameter is smaller than 10 nm, the resin emulsion has a higherviscosity. Therefore, it is sometimes difficult to obtain an inkviscosity dischargeable in a printer. When the average particle diameteris larger than 300 nm, the printer nozzle may clog with the particles,causing discharge malfunction.

The silicone content from the silicone modified acrylic resin ispreferably 100 ppm to 400 ppm. When the silicon content is lower than100 ppm, a coating having excellent abrasion properties and markerresistance may not be obtained. When it is higher than 400 ppm, itbecomes highly hydrophobic and may become less stable in the ink.

The silicone modified acrylic resin preferably has the minimum filmforming temperature of 20° C. or lower. When the minimum film formingtemperature is more than 20° C., sufficient fixing properties may not beobtained. In other words, the pigments may be released and smear theprint medium when the printed part is rubbed or crossed over with amarker.

The addition rate of pigments as the colorant in the recording ink ispreferably 0.5% by mass to 25% by mass, more preferably 2% by mass to15% by mass. Generally, the image concentration is increased and ahigher image quality is obtained as the pigment concentration isincreased. On the other hand, adverse effects on fixing properties andreliability including stable discharge and clogging easily appear.However, the present invention ensures the fixing properties whilemaintaining the reliability including stable discharge and clogging evenwhen the pigment addition rate is increased.

—Water-Soluble Organic Solvent—

The recording ink of the present invention uses water as a solutionmedium. However, the following water-soluble organic solvents can beused for giving desired physical properties to the ink, for preventingthe ink from drying, or for improving the dissolution stability of thecompound of the present invention. Examples of the water-soluble organicsolvent include polyvalent alcohols such as ethylene glycol, diethyleneglycol, triethylene glycol, polyethylene glycol, polypropylene glycol,1,3-propanediol, 1,3-butane diol, 1,4-butane diol,3-methyl-1,3-butandiol, 1,5-pentanediol, 1,6-hexanediol, glycerin,1,2,6-hexanetriol, 1,2,4-butanetriol, 1,2,3-butanetriol, petriol,3-methyl-1,3-butanediol, 2,3-butanediol, tetraethylene glycol,2-methyl-2,4-pentanediol, and thiodiglycol, polyvalent alcohol alkylethers such as ethylene glycol monoethyl ether, ethylene glycolmonobutyl ether, diethylene glycol monomethyl ether, diethylene glycolmonoethyl ether, diethylene glycol monobutyl ether, tetraethylene glycolmonomethyl ether, and propylene glycol monoethyl ether, polyvalentalcohol aryl ethers such as ethylene glycol monophenyl ether andethylene glycol monobenzyl ether; nitrogen-containing heterocycliccompounds such as N-methyl-2-pyrrolidone, N-hydroxyethyl-2-pyrrolidone,2-pyrrolidone, 1,3-dimethylimidazolidinone, and ε-caprolactam; amidessuch as formamide, N-methylformamide, formamide, andN,N-dimethylformamide; amines such as monoethanolamine, diethanolamine,triethanolamine, monoethylamine, diethylamine, and triethylamine,sulfur-containing compounds such as dimethylsulfoxide, sulfolane, andthiodiethanol, propylene carbonate, ethylene carbonate, γ-butylolactoneand the like. These solvents may be used individually or in combinationof two or more. Among them, glycerin, ethylene glycol, diethyleneglycol, triethylene glycol, propylene glycol, dipropylene glycol,tripropylene glycol, 1,3-butanediol, 2,3-butanediol, 1,4-butanediol,3-methyl-1,3-butanediol, 1,5-pentanediol, tetraethylene glycol,1,6-hexanediol, 2-methyl-2,4-pentanediol, polyethylene glycol,1,2,4-butanetriol, 1,2,6-hexanetriol, thiodiglycol, 2-pyrrolidone,N-methyl-2-pyrrolidone, and N-hydroxyethyl-2-pyrrolidone is preferable.3-methyl-1,3-butanediol is specifically preferable.

The content of the water-soluble organic solvent in the recording ink ispreferably 10% by mass to 50% by mass, more preferably 20% by mass to40% by mass.

The recording ink of the present invention may contain otherwater-soluble organic solvents where necessary in combination with thewater-soluble organic solvents. For example, saccharides are preferableas the other water-soluble organic solvents. Examples of the saccharidesinclude monosaccharides, disaccharides, oligosaccharides (includingtrisaccharides and tetrasaccharides), polysaccharides, and theirderivatives. Among them, glucose, mannose, fructose, ribose, xylose,arabinose, galactose, maltose, cellobiose, lactose, sucrose, trehalose,and maltotriose are preferable. Here, polysaccharides refer to a broaderrange of sugar including naturally existing substances such asα-cyclodextrin and cellulose.

Examples of the derivatives of the saccharides include reducing sugar ofthe saccharides (for example, sugar alcohols (those expressed by ageneral formula: HOCH₂(CHOH)_(n)CH₂OH (in which n is an integer of 2 to5)), oxidized sugar (for example aldonic acid and uronic acid), aminoacid, and thioic acid. Among these, sugar alcohols are preferable.Examples of the sugar alcohols include maltitol and sorbit.

The content of the saccharides in the recording ink is preferably 0.1%by mass to 40% by mass, more preferably 0.5% by mass to 30% by mass.

The recording ink of the present invention may contain urea oralkylglycine where desired. Examples of the urea include urea, thiourea,ethyleneurea, and 1,3-dimethyl-2-imidazolidinone. Examples of thealkylglycine include N-methylglycine, N,N-dimethylglycine, andN-ethylglycine. Basically, both urea and alkylglycine serve to maintainexcellent moisture retention property in aqueous ink (leading toimproved storage stability) and exert excellent effects on stabledischarge and anti-clogging of the recording head of an inkjet printer.Further, they are useful for adjusting viscosity and surface tension ofthe ink. Excellent anti-clogging property prevents the head fromclogging. Defective discharge such as deviating ink droplets can beprevented during ink discharge.

Generally, the addition rate of the urea and alkylglycine in therecording ink is preferably 0.5% by mass to 50% by mass, more preferably1% by mass to 20% by mass. When the addition rate is smaller than 0.5%by mass, desired requirements on an inkjet printer recording head maynot be satisfied. When it is higher than 50% by mass, it causes highviscosity and may lead to adverse effects on ink storage stability anddefective discharge.

The other components are not particularly limited and may beappropriately selected according to the purpose. For example, pHadjusters, preservatives/fungicides, rust prevention agents,antioxidants, ultraviolet absorbers, oxygen absorbers, and lightstabilizers may be used.

Examples of the preservatives/fungicides include1,2-benzisothiazoline-3-on, sodium dehydroacetate, sodium sorbate,2-pyridinethiol-1-oxide sodium, sodium benzoate, and pentachlorophenolsodium, and the like.

The pH adjusters are not particularly limited and any substances may beused according to the purpose as long as they can be used to adjust thepH for 7 or higher without adverse effects on the ink to be prepared.

Examples of the pH adjusters include amines such as diethanolamine andtriethanolamine, alkali metal hydroxides such as lithium hydroxide,sodium hydroxide, and potassium hydroxide; ammonium hydroxide,quaternary ammonium hydroxide, quaternary phosphonium hydroxide, andalkali metal carbonates such as lithium carbonate, sodium carbonate, andpotassium carbonate, and the like.

Examples of the rust prevention agents include acidic sulfite, sodiumthiosulfate, anmone thioglycolate, diisopropylammoniumnitrite,pentaerythritol tetranitrate, dicyclohexylammoniumnitrite, and the like.

Examples of the antioxidants include phenolic antioxidants (includinghindered phenolic antioxidants), amine antioxidants, sulfurantioxidants, phosphorus antioxidants, and the like.

Examples of the phenolic antioxidants (including hindered phenolicantioxidants) include butylated hydroxyanisole,2,6-di-tert-butyl-4-ethylphenol,stearyl-β-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate,2,2′-methylenebis(4-methyl-6-tert-butylphenol),2,2′-methylenebis(4-ethyl-6-tert-butylphenol),4,4′-butylidenebis(3-methyl-6-tert-butylphenol),1,1,3-tris(2-methyl-4-hydroxy-5-tert-butylphenyl)butane,1,3,5-trimethyl-2,4,6-tris(3,5-di-tert-butyl-4-hydroxybenzyl)benzene,tetrakis[methylene-3-(3′,5′-di-tert-butyl-4′-hydroxyphenyl)propionate]methane,and the like.

Examples of the amine antioxidants include phenyl-β-naphthylamine,α-naphthylamine, N,N′-di-sec-butyl-p-phenyldiamine, phenothiazine,N,N′-diphenyl-p-phenylenediamine, 2,6-di-tert-butyl-p-cresol,2,6-di-tert-butylphenol, 2,4-dimethyl-6-tert-butyl-phenol,butylhydroxyanisole, 2,2′-methylenebis(4-methyl-6-tert-butylphenol),4,4′-butylidenebis(3-methyl-6-tert-butylphenol),4,4′-thiobis(3-methyl-6-tert-butylphenol),tetrakis[methylene-3(3,5-di-tert-butyl-4-dihydroxyphenyl)propionate]methane,1,1,3-tris(2-methyl-4-hydroxy-5-tert-butylphenyl)butane, and the like.

Examples of the sulfur antioxidants include dilauryl3,3′-thiodipropionate, distearylthiopropionate,laurylstearylthiopropionate, dimyristyl 3,3′-thiodipropionate, distearylβ,β′-thiodipropionate, 2-mercaptobenzoimidazole, dilaurylsulfide, andthe like.

Examples of the phosphorus antioxidants include triphenylphosphite,octadecylphosphite, triisodecylphosphite, trilauryltrithiophosphite,trinonylphenylphosphite, and the like.

Examples of the ultraviolet absorbers include benzophenone,benzotriazole, salicylate, cyanoacrylate, nickel complex saltultraviolet absorbers, and the like.

Examples of the benzophenone ultraviolet absorbers include2-hydroxy-4-n-octoxybenzophenone, 2-hydroxy-4-n-dodecyloxybenzophenone,2,4-dihydroxybenzophenone, 2-hydroxy-4-methoxybenzophenone,2,2′,4,4′-tetrahydroxybenzophenone, and the like.

Examples of the benzotriazole ultraviolet absorbers include2-(2′-hydroxy-5′-tert-octylphenyl)benzotriazole,2-(2′-hydroxy-5′-methylphenyl)benzotriazole,2-(2′-hydroxy-4′-octoxyphenyl)benzotriazole,2-(2′-hydroxy-3′-tert-butyl-5′-methylphenyl)-5-chlorobenzotriazole, andthe like.

Examples of the salicylate ultraviolet absorbers includephenylsalicylate, p-tert-butylphenylsalicylate, p-octylphenylsalicylate,and the like.

Examples of the cyanoacrylate ultraviolet absorbers includeethyl-2-cyano-3,3′-diphenylacrylate,methyl-2-cyano-3-methyl-3-(p-methoxyphenyl)acrylate, andbutyl-2-cyano-3-methyl-3-(p-methoxyphenyl)acrylate.

Examples of the nickel complex salt ultraviolet absorbers includenickelbis(octylphenyl)sulfide,2,2′-thiobis(4-tert-octylphelate)-n-butylaminenickel (II),2,2-thiobis(4-tert-octylphelate)-2-ethylhexylaminenickel (II),2,2′-thiobis(4-tert-octylphelate)triethanolaminenickel (II), and thelike.

The recording ink of the present invention is produced by dispersing ordissolving at least water, a colorant, and at least one fluorochemicalsurfactant selected from the above Structural Formulae (1) to (3) and,where necessary, other components in an aqueous medium and, wherenecessary, stirring/mixing them. The dispersing can be done by, forexample, a sand mill, a homogenizer, a ball mill, a paint shaker, or anultrasonic disperser. The stirring/mixing can generally be done by, forexample, a stirrer having stirring blades, a magnetic stirrer, or a highspeed disperser.

Physical properties of the recording ink of the present invention arenot particularly limited and may be appropriately selected according tothe purpose. For example, the recording ink of the present inventionpreferably has the following ranges of viscosity, surface tension, andpH.

The viscosity is preferably 5 mPa·sec to 20 mPa·sec., more preferably 5mPa·sec. to 10 mPa·sec., at 25° C. When the viscosity is higher than 20mPa·sec., it becomes difficult to ensure stable discharge.

The surface tension is preferably 22 mN/m to 55 mN/m at 20° C. When thesurface tension is lower than 22 mN/m, running ink is noticeable onpapers and stable jet may not be obtained. When it is higher than 55mN/m, the ink does not sufficiently infiltrate into papers, which mayprolong drying time.

The pH is, for example, preferably 7 to 10.

The coloring of the recording ink of the present invention is notparticularly limited and may be appropriately selected according to thepurpose. Yellow, magenta, cyan, and black can be used. An ink setcomprising a combination of two or more of these colorings can be usedin recording to form multicolor images. An ink set comprising all thecolorings can be used in recording to form full color images.

The recording ink of the present invention can be successfully used inprinters provided with any types of inkjet heads including a piezo-typein which a piezoelectric element is used to pressurize ink in the inkpassage, a diaphragm forming the wall of the ink passage is deformed tochange the inner volume of the ink passage, thereby discharging inkdroplets (Japanese Patent Application Laid-Open (JP-A) No. 02-51734), athermal type in which an exothermic resistor is used to heat ink in theink passage to produce bubbles (Japanese Patent Application Laid-Open(JP-A) No. 61-59911), and an electrostatic type in which a diaphragmforming the wall of the ink passage and electrodes are placed at facingpositions and electrostatic force is produced between the diaphragm andthe electrodes to deform the diaphragm and change the inner volume ofthe ink passage, thereby discharging ink droplets (Japanese PatentApplication Laid-Open (JP-A) No. 06-71882).

The recording ink of the present invention can be preferably used in avariety of fields. It can be preferably used in image forming apparatus(such as printers) of an inkjet recording system. For example, therecording ink of the present invention can be used in a printer having afunction to heat recording papers and the recording ink to 50° C. to200° C. before, during, or after printing, thereby urging ink fixing.Particularly, the recording ink of the present invention can bepreferably used in the ink cartridge, ink record, inkjet recordingapparatus, and inkjet recording method of the present inventiondescribed hereinafter.

(Ink Cartridge)

The ink cartridge of the present invention comprises a containercontaining the recording ink of the present invention and otherappropriated selected members as required.

The container is not particularly limited and its shape, structure,size, and material are appropriately selected according to the purpose.Preferred embodiments include those at least having an ink pouch formedby aluminum laminated film or resin film.

The ink cartridge is hereainafter described with reference to FIGS. 1and 2. FIG. 1 is an illustration showing an embodiment of the inkcartridge of the present invention. FIG. 2 is an illustration of the inkcartridge of FIG. 1 including a case (exterior).

In an ink cartridge 200, as shown in FIG. 1, an ink pouch 241 is filledthrough an ink inlet 242. The ink inlet 242 is closed by fusion bondingafter the air is exhausted. An ink outlet 243 made of a rubber materialis pierced by a needle on the apparatus body for use, thereby the ink issupplied to the apparatus.

The ink pouch 241 is formed by a packaging member such as anon-permeable aluminum laminated film. The ink pouch 241 is housed in acartridge case 244 generally made of plastics as shown in FIG. 2 anddetachably mounted on various types of inkjet recording apparatus.

The ink cartridge of the present invention contains the recording ink(ink set) of the present invention. The ink cartridge of the presentinvention can be detachably mounted on variety types of inkjet recordingapparatus and it is particularly preferable that the ink cartridge ofthe present invention is detachably mounted on the inkjet recordingapparatus of the present invention described later.

(Inkjet Recording Apparatus and Inkjet Recording Method)

The first embodiment of the inkjet recording apparatus of the presentinvention at least comprises an ink drops discharging unit configured todischarge the recording ink drops to form an image by applying impulseto the recording ink and, where necessary, further comprises otherappropriately selected units such as an impulse generation unit and acontrol unit.

The second embodiment of the inkjet recording apparatus of the presentinvention at least comprises an ink drops discharging unit configured todischarge the recording ink drops to form an image by applying impulseto the recording ink and, where necessary, further comprises otherappropriately selected units such as an impulse generation unit and acontrol unit.

The ink drops discharging unit is a nozzle head portion having asilicone resin-containing ink repellent layer on the ink dischargingsurface and the ink used in the inkjet recording apparatus contains atleast water, a colorant, a fluorochemical surfactant, and anaminopropanediol compound.

The first embodiment of the inkjet recording method of the presentinvention at least comprises an ink drops discharging step ofdischarging the recording ink drops to form an image by applying impulseto the recording ink and, where necessary, further comprises otherappropriately selected steps such as an impulse generation step and acontrol step.

The second embodiment of the inkjet recording method of the presentinvention at least comprises an ink drops discharging step ofdischarging the recording ink drops to form an image by applying impulseto the recording ink, where necessary, further comprises otherappropriately selected steps such as an impulse generation step and acontrol step.

The ink drops discharging is performed using a nozzle head portionhaving a silicone resin-containing ink repellent layer on the inkdischarging surface and the ink used in the inkjet recording methodcontains at least water, a colorant, a fluorochemical surfactant, and anaminopropanediol compound.

The inkjet recording method of the present invention is preferablyperformed in the inkjet recording apparatus of the present invention.The ink drops discharging step is preferably performed by the ink dropsdischarging unit. Further, the other steps are preferably performed bythe other units.

—Ink Drops Discharging Step and Ink Drops Discharging Unit—

The ink drops discharging step is a step of discharging the ink drops toform an image by applying impulse to the ink.

The ink drops discharging unit is a unit configured to discharge the inkdrops to form an image by applying impulse to the ink.

The ink drops discharging unit is not particularly limited and may beappropriately selected according to the purpose. Examples of the dropsdischarging unit include (1) a piezo-type nozzle head in which apiezoelectric element is used to pressurize ink in the ink passage, adiaphragm forming the wall of the ink passage is deformed to change theinner volume of the ink passage, thereby discharging ink droplets(Japanese Patent Application Laid-Open (JP-A) No. 02-51734), (2) athermal type nozzle head in which an exothermic resistor is used to heatink in the ink passage to produce bubbles (Japanese Patent ApplicationLaid-Open (JP-A) No. 61-59911), and (3) an electrostatic type nozzlehead in which a diaphragm forming the wall of the ink passage andelectrodes are placed at facing positions and electrostatic force isproduced between the diaphragm and the electrodes to deform thediaphragm and change the inner volume of the ink passage, therebydischarging ink droplets (Japanese Patent Application Laid-Open (JP-A)No. 06-71882).

The nozzle head preferably has a silicone-containing ink repellent layeron the ink discharging surface. In the present invention, the inkrepellent layer is made of a silicone resin-containing structure so thatit maintains sufficient ink repellency to a fluorochemicalsurfactant-containing ink.

The silicone resin-containing structure is a structure of silicone resinby itself or in combination with other components such as other resinsand metals. Examples of effective structures include (1) silicone resinfine-particles dispersed in a fluororesin, (2) a kneaded mixture ofsilicone resin and polypropylene, and (3) silicone resin/Ni eutectoidplating. Among them, a mixture of silicone resin and other components iseffective for preventing the silicone resin from eluting from the inkrepellent layer.

The silicone resin is a resin having as a basic skeleton a siloxane bondconsisting of Si and O and commercially available in a variety of formssuch as oils, resins, and elastomers. In addition to water-repellency,which is important in the present invention, the silicone resin has avariety of characteristics such as heat resistance, release property,anti-foaming, and adhesiveness. The silicone resin can be cold curable,heat curable, or UV curable, being selectively used according toproduction methods and applications.

The method of forming a silicon resin-containing ink repellent layer ona nozzle surface is not particularly limited and may be appropriatelyselected according to the purpose. Examples of the method include (1)vacuum deposition of a liquid silicone resin material, (2) plasmapolymerization of an silicone oil, (3) application such as spin coating,dipping, and spray coating, and (4) electrodeposition.

In forming a silicone resin layer by any method except forelectrodeposition, the nozzle hole and nozzle back surface are maskedwith photoresist or water-soluble resin and the resist is peeled off andremoved after the formation of the silicone resin layer, thereby asilicone resin ink repellent layer can be formed only on the frontsurface of the nozzle plate. In such a case, a strong alkali releasantis not preferable because it may damage the silicone resin layer.

The thickness of the silicon resin layer as the ink repellent layer isnot particularly limited and may be appropriately selected according tothe purpose. The thickness is preferably 0.1 μm to 5.0 μm, morepreferably 0.1 μm to 1.0 μm. When the thickness is smaller than 0.1 μm,mechanical resistances such as wiping resistance and abrasion resistancemay be deteriorated.

When it is larger than 5.0 μm, the adhesion between the silicone resinlayer and the substrate may be deteriorated or uneven ink repellency maybe obtained.

It is preferable that the liquid chamber, fluid dragging part,diaphragm, and nozzle member of the nozzle head part be at least partlymade of materials containing at least either silicon or nickel.

The nozzle diameter of the nozzle head part is preferably 50 μm or lessand more preferably him to 30 μm. It is preferable that subtanks forsupplying ink be provided on the inkjet head and the ink is supplied tothe subtanks from the ink cartridge via supply tubes.

The impulse may be generated by, for example, the impulse generationunit. The impulse is not particularly limited and may be appropriatelyselected according to the purpose. Examples of the impulse include heat(temperature), pressure, vibration, and light. These can be usedindividually or in combination or two or more. Among them, heat andpressure are preferable.

The impulse generation unit may be, for example, a heating apparatus, apressurizing apparatus, a piezoelectric element, a vibration generationapparatus, an ultrasonic oscillator, or a light. Specifically, examplesof the impulse generation unit include a piezoelectric actuator such asa piezoelectric element, a thermal actuator using an electrothermalconversion element such as an exothermic resistor to cause film boilingand, accordingly, phase change of a liquid, a shape-memory alloyactuator using metal phase changes due to temperature changes, anelectrostatic actuator using electrostatic force.

The aspect of the ink drops discharging is not particularly limited, andvaries depending on the type of the impulse. For example, when theimpulse is “heat,” thermal energy corresponding to recording signals isapplied to the ink in the recording head, for example, using a thermalhead, the thermal energy causes the ink to bubble, and the bubblepressure urges the ink to be discharged as ink droplets from the nozzlehole of the recording head. When the impulse is “pressure,” for example,an electric voltage is applied to a piezoelectric element bonded at aposition called a pressure chamber within the ink passage of therecording head, the piezoelectric element is bent and the pressurechamber is reduced in volume, thereby the ink is discharged as dropletsfrom the nozzle hole of the recording head.

The discharged ink droplets preferably have a particle size of 3 pl to 4pl, a discharge jet speed of 5 m/sec to 20 m/sec, a driving frequency of1 kHz or higher, and a resolution of 300 dpi or higher.

The control unit is not particularly limited and may be appropriatelyselected according to the purpose as long as it is capable ofcontrolling the operation of each unit. Examples of the control unitinclude devices such as a sequencer and a computer.

The ink used in the second embodiment of the inkjet recording method andinkjet recording apparatus contains at least water, a colorant, afluorochemical surfactant, and an aminopropanediol compound and, wherenecessary, further contains other components.

—Aminopropanediol Compound—

The aminopropanediol compound is a water-soluble organic basic compoundand preferably, for example, aminopropanediol derivatives.

The aminopropanediol derivatives are not particularly limited and may beappropriately selected according to the purpose. Examples of theaminopropanediol derivatives include 1-amino-2,3-propanediol,1-methylamino-2,3-propanediol, 2-amino-2-methyl-1,3-propanediol, and2-amino-2-ethyl-1,3-propanediol. Among them,2-amino-2-ethyl-1,3-propanediol is particularly preferable.

The 2-amino-2-ethyl-1,3-propanediol is excellent in view ofanti-clogging and stable discharge in addition to significant effects onpreventing the silicone resin from eluting from the ink repellent layerforming a printer nozzle member, which is the purpose of the presentinvention.

The addition rate of the aminopropanediol compound in the ink ispreferably 0.01% by mass to 10% by mass, more preferably 0.1% by mass to5.0% by mass, further preferably 0.1% by mass to 2.0% by mass. Theaddition rate of the aminopropanediol compound is adjusted according tothe type and content of colorants and ultimately determines the optimumvalues for an inkjet recording apparatus. When the addition rate isexcessively low, the elution preventive effect on the silicone resinlayer of the nozzle member may not observed. Excessively high rates mayincrease pH, which may otherwise adversely affect reliability and causedemerits such as increased viscosities.

—Fluorochemical Surfactant—

The fluorochemical surfactant is added to ink so as to stably dispersecolorants in the ink and improve ink wettability to papers, therebyimages having improved color development and less running ink can beobtained.

The fluorochemical surfactant is not particularly limited and may beappropriately selected according to the purpose. Examples of thefluorochemical surfactant include perfluoroalkylsulfonate,perfluoroalkylcarboxylate, perfluoroalkylphosphoric ester,perfluoroalkylethyleneoxide adducts, perfluoroalkylbetaine,perfluoroalkylamineoxide compounds, and compounds having the followingStructural Formula (A). Among them, the compounds having the followingStructural Formula is preferable in view of reliability.CF₃CF₂(CF₂CF₂)_(j)—CH₂CH₂O(CH₂CH₂O)_(k)H  Structural Formula (A)

where, j and k are integers; j is preferably of 0 to 10 and k ispreferably of 0 to 40 in the Structural Formula (A) above.

Commercially available fluorochemical surfactants can be used, includingSurflon S-111, S-112, S-113, S-121, S-131, S-132, S-141, and S-145 (byAsahi Glass Co., Ltd.); FLUORAD FC-93, FC-95, FC-98, FC-129, FC-135,FC-170C, FC-430, FC-431, and FC4430 (by Sumitomo 3M Limited); MegafackF-470, F-1405, and F-474 (by Dainippon Ink & Chemicals Inc.); ZonylFS-300, FSN, FSN-100, FSO (by DuPont Kabushiki Kaisha); EFTOP EF-351,EF-352, EF-801, and EF-802 (by JEMCO Inc). Among them, Zonyl FS-300,FSN, FSN-100, and FSO (by DuPont Kabushiki Kaisha) are particularlypreferable in view of excellent reliability and improved colordevelopment. These commercially available products are often a mixtureof several compounds having different molecular masses (in theStructural Formula (A) above, j and k have distributions). However, theyare approved for the efficacy of the present invention without anyproblems.

Among other preferable fluorochemical surfactants, at least one selectedfrom the Structural Formulae (1) to (3) above in the recording ink ispreferable.

The same colorants and other components as the recording ink can beused.

An embodiment of the inkjet recording method of the present inventionusing the inkjet recording apparatus of the present invention isdescribed hereinafter, with reference to the drawings. An inkjetrecording apparatus shown in FIG. 3 comprises an apparatus body 101, afeeder tray 102 attached to the apparatus body 101 for feeding papers,paper output tray 103 attached to the apparatus body 101 for receivingpapers on which images are recorded (formed), and an ink cartridgemounting part 104. An operation part 105 having operation keys andindicators is provided on the top surface of the ink cartridge mountingpart 104. The ink cartridge mounting part 104 has a front cover 115 thatcan be opened and/or closed to remove and/or place ink cartridges 201.

As shown in FIGS. 4 and 5, a carriage 133 is supported slidably in thescan direction by a guide rod 131 that is a guide member laid across notshown right and left side plates and a stay 132 and moved by a mainmotor (not shown) in the arrowed directions in FIG. 5 for scanningwithin the apparatus body 101.

Recording heads 134 consisting of four inkjet recording heads thatdischarge yellow (Y), cyan (C), magenta (M), and black (B) recording inkdroplets, respectively, have ink discharge ports arranged in theintersecting direction with the main scanning direction and they areplaced with their ink discharge direction downward.

Inkjet recording heads constituting the recording heads 134 are providedwith an energy generation unit for discharging recording ink such as apiezoelectric actuator such as an piezoelectric element, a thermalactuator using an electrothermal conversion element such as anexothermic resistor to cause film boiling and, accordingly, phase changeof a liquid, a shape-memory alloy actuator using metal phase changes dueto temperature changes, and an electrostatic actuator usingelectrostatic force.

The carriage 133 is provided with subtanks 135 for supplying each colorink to the recording heads 134. The subtanks 135 are filled with therecording ink of the present invention from the ink cartridge 201 of thepresent invention mounted in the ink cartridge mounting part 105 via anot-shown recording ink supply tube.

On the other hand, a paper feed part for feeding paper 142 stuck on apaper load part (platen) 141 of the feed tray 102 comprises a half-moonroller (a feed roller 143) that separates and supplies the paper 142from the paper load part 141 one by one and a separation pad 144 thatfaces the feed roller 143 and is made of a large friction coefficientmaterial. The separation pad 144 is biased toward the feed roller 143.

A conveying part for conveying the paper 142 supplied from the feed partunderneath the recording heads 134 comprises a conveying belt 151 forelectrostatically adsorbing and conveying the paper 142, a counterroller 152 for conveying the paper 142 sent from the paper feed part viaa guide 145 by clamping it together with the conveying belts 151, aconveying guide 153 for turning the paper 142 sent nearly vertically by90° so as to lay it on the conveying belt 151, and a leading endpressure roller 155 that is biased toward the conveying belt 151 by apresser member 154. A charging roller 156 that is a charging unit forcharging the surface of the conveying belt 151 is also provided.

The conveying belt 151 is an endless belt, being placed over conveyingroller 157 and a tension roller 158 and running around in the beltconveying direction. For example, the conveying belt 151 has a frontlayer that is a paper adsorbing surface made of a dragging-uncontrolledresin, for example a copolymer of tertafluoroethylene and ethylene(ETFE), having a thickness of 40 μm and a back layer (an intermediatedragging layer or an earth layer) made of the same material as the frontlayer, but dragging-controlled with carbon. A guide member 161 isprovided behind the conveying belt 151 at the corresponding position tothe printing area by the recording heads 134. An output part fordischarging the paper 142 on which recording was done by the recordingheads 134 comprises a separation click 171 for separating the paper 142from the conveying belt 151, paper output roller 172, and an paperoutput roller 173. Paper output tray 103 is disposed below paper outputroller 172.

A double-side feed unit 181 is detachably mounted in the back of theapparatus body 101. The double-side feed unit 181 takes in the paper 142that is moved backward as the conveying belt 151 is rotated in thereverse direction, turns it over, and feeds it again between the counterroller 152 and the conveying belt 151. A manual feeder 182 is providedon the top surface of the double-side feed unit 181.

In this inkjet recording apparatus, the paper 142 is separated and fedfrom the paper feed part one by one. Being fed vertically, the paper 142is guided by the guide 145 and conveyed between the conveying belt 151and the counter roller 152. Then, it is guided by the conveying guide153 at the leading end and is pressed against the conveying belt 151 bythe leading end pressure roller 155 to change the convey directionnearly by 90°.

Meanwhile, the conveying belt 157 is charged by the charging roller 156and the paper 142 is electrostatically adsorbed and conveyed by theconveying belt 151. Then, the recording heads 134 are driven accordingto image signals while the carriage 133 is moved. Ink droplets aredischarged on the paused paper 142 for recording one-line. Then, thepaper 142 is conveyed by a certain rate for recording the next line.Receiving a recording end signal or a signal indicating the rear end ofthe paper 142 has reached the recording area, the recording operation isterminated and the paper 142 is discharged to the paper output tray 103.

When it is detected that the remaining amount of the recording ink inthe subtank 135 is nearly to the end, a certain amount of recording inkis supplied to the subtank 135 from the ink cartridge 201.

In this inkjet recording apparatus, when the recording ink in the inkcartridge 201 of the present invention is used up, the case of the inkcartridge 201 is disassembled and only the ink pouch contained thereincan be exchanged. The ink cartridge 201 allows for stable recording inksupply even in a vertical and front mounting structure. Therefore, whenthe apparatus body 101 is installed with the top being blocked bysomething, for example, the ink cartridge 210 can be housed in a rack.Even if something is placed on the top surface of the apparatus body101, the ink cartridge 201 can be easily replaced.

Here, the explanation is made with reference to an application in aserial type (shuttle type) inkjet recording apparatus in which thecarriage scans is described. A line type inkjet recording apparatushaving a line head is also applicable.

The inkjet recording apparatus and inkjet recording method of thepresent invention are applicable to various recording in an inkjetrecording system. For example, the inkjet recording apparatus and inkjetrecording method of the present invention can be particularly preferablyapplied to inkjet recording printers, facsimiles, copy machines, andprinter/fax/copy complex machines.

An inkjet head to which the present invention is applied is describedhereinafter.

FIG. 6 is an enlarged view of the core part of the inkjet head accordingto an embodiment of the present invention. FIG. 7 is an enlargedcross-sectional view of the core part of the same head in theinter-channel direction.

This inkjet head comprises a frame 10 having cutouts serving as an inksupply port (not shown) and a common liquid chamber 1 b, a passage plate20 having cutouts serving as a fluid dragging part 2 a and a pressurizedliquid chamber 2 b and a communication port 2 c that communicates to anozzle 3 a, a diaphragm 60 having a raised part 6 a, a diaphragm part 6b, and an ink inflow port 6 c, a laminated piezoelectric element 50connected to the diaphragm 60 via an adhesive layer 70, and a base 40 onwhich the laminated piezoelectric element 50 is fixed.

The base 40 is made of barium titanate ceramics, on which two rows oflaminated piezoelectric element 50 are arranged and connected.

The piezoelectric element 50 consists of alternately laminatedpiezoelectric layers of lead zirconate titanate (PZT) having a thicknessof 10 μm to 50 μm per layer and internal electrode layers of silverpalladium (AgPd) having a thickness of several Jim per layer. Theinternal electrode layers are connected to external electrodes at bothends.

The laminated piezoelectric element 50 is divided into a comb-like shapeby half-cut dicing, having driving parts 5 f and supporting parts(non-driving part) 5 g every other division. The exterior of theexternal electrodes is processed, for example notched, for limiting onlength, thereby being divided by half-cut dicing. Multiple separateelectrodes are formed. Not divided by dicing, the other is conductiveand serves as a common electrode.

A FPC8 is soldered to the individual electrodes of the driving part. Thecommon electrode is turned in an electrode layer provided at the end ofthe laminated piezoelectric layer and connected to the Gnd electrode ofthe FPC8. An un-shown driver IC is mounted on the FPC8 to control theapplication of driving voltage to the driving part 5 f.

As for the diaphragm 60, a thin film diaphragm part 6 b, anisland-shaped raised part (island part) 6 a formed at the center of thediaphragm part 6 b and connected to the laminated piezoelectric element50 serving as the driving parts 5 f, a thick part including beams to beconnected to the supporting part, and an opening serving as in inkinflow port 6 c are formed by electroforming two nickel plated films.The diaphragm has a thickness of 3 μm and a width (one side) of 35 μm.

The connections between the island part 6 a of the diaphragm 60 and themovable parts 5 f of the laminated piezoelectric element 50 and betweenthe diaphragm 50 and the frame 10 are made by patterning the adhesivelayer 70 including a gap material.

The passage plate 20 is made of a silicon mono-crystalline substrate, inwhich cutouts serving as a liquid dragging part 2 a and a pressurizedliquid chamber 2 b and a through-hole provided at the correspondingposition to the nozzle 3 a and serving as a communication port 2 c arepatterned by etching.

The remaining part after the etching serves as a partition wall 2 d ofthe pressurized liquid chamber 2 b. In this head, a part etched in asmaller width serves as the liquid dragging part 2 a.

The nozzle plate 30 is made of a metal material such as a nickel platedfilm formed by electroforming and has a number of nozzles 3 a serving asfine discharge openings for discharging ink droplets. The nozzle 3 a hasa horn-like (nearly cylindrical or nearly truncated cone) internal shape(inner shape). The nozzle 3 a has a diameter of approximately 20 μm to35 μm at the ink droplets discharge side. The nozzle pitch in each rowis 150 dpi.

The ink discharging surface (nozzle front side) of the nozzle plate 30is provided with a water-repellent finish layer 3 b having a not shownwater-repellent finish surface. A water-repellent finish film selectedaccording to ink's physical properties such as PTFE-Ni eutectoid platingand electrodeposition of fluororesin, deposition of volatilefluororesin, silicone resin and fluororesin solvent application andbaking can be provided to stabilize ink droplet shapes and dischargingproperty and, thus, ensure a high image quality. Among them, for examplemany fluororesins are known; excellent water-repellency can be obtainedby depositing modified perfluoropolyoxethane (by Daikin Industies, Ltd,trade name: Optool DSX) to a thickness of 30 Å to 100 Å.

The frame 10 in which cutouts serving as an ink supply inlet and acommon liquid chamber 1 b are formed is made by molding a resin.

In an inkjet head having the above structure, a driving waveform (10V to50V pulse voltage) is applied to the driving part 5 f according torecording signals. The driving part 5 f is shifted in the laminationdirection. The pressurized liquid chamber 2 b is pressurized via thediaphragm 30 and the pressure is increased, thereby ink droplets aredischarged through the nozzle 3 a.

After the ink droplets discharge is completed, the ink pressure in thepressurized liquid chamber 2 b is decreased. The inertia ink flow anddriving pulse discharge process causes negative pressure within thepressurized liquid chamber 2 b, leading to the ink supply process.Meanwhile, the ink supplied from the ink tank enters the common liquidchamber 1 b and further fills the pressurized liquid chamber 2 b fromthe common liquid chamber 1 b via the ink inflow port 6 c and fluiddragging part 2 a.

The fluid dragging part 2 a effectively attenuates residual pressurefluctuation while it stands against recharging (refilling) due tosurface tension. Appropriately selected dragging part balances residualpressure attenuation with refilling time and shortens the transitiontime to the next ink droplets discharge operation (driving cycle).

(Ink Record)

The ink record recorded by the inkjet recording apparatus and inkjetrecording method of the present invention is the ink record of thepresent invention. The ink record of the present invention comprisesimages formed on recording media using the recording ink of the presentinvention.

The recording media are not particularly limited and may can beappropriately selected according to the purpose. Examples of therecording media include regular papers, glossy papers, special papers,cloths, films, and OHP sheets. These can be used individually or incombination of two or more.

The ink record has high quality, no running ink, and excellent temporalstability, thereby being preferably used in various applications asdocuments in which various texts and images are recorded.

EXAMPLES

Examples of the present invention are described hereinafter. However,the present invention is not limited to these examples. All percentagesand parts are by mass unless indicated otherwise.

Preparation Example 1

—Preparation of Copper Phthalocyanine Pigment-Containing PolymerFine-Particles Dispersion—

An additional test preparation was conducted with reference toPreparation Example 3 of Japanese Patent Application Laid-Open (JP-A)No. 2001-139849.

First, for preparing a polymer solution, the inside of a 1 L flaskequipped with a mechanical stirrer, a thermometer, a nitrogen gas inlettube, a reflux tube, and a dropping funnel was sufficiently purged withnitrogen gas. Then, 11.2 g of styrene, 2.8 g of acrylic acid, 12.0 g oflaurylmethacrylate, 4.0 g of polyethylene glycol methacrylate, 4.0 g ofstyrene macromer (by To a Gosei Co., Ltd., trade name: AS-6), and 0.4 gof mercaptoethanol were introduced and heated to 65° C. A mixed solutionof 100.8 g of styrene, 25.2 g of acrylic acid, 108.0 g oflayrylmethacrylate, 36.0 g of polyethylene glycol methacrylate, 60.0 gof hydroxyethylmethacrylate, 36.0 g of styrene macromer (by To a GoseiCo., Ltd., trade name: AS-6), 3.6 g of mercaptoethanol, 2.4 g ofazobisdimethylvaleronitrile, and 18 g of methylethylketone was added indrops to the flask over 2.5 hours, following which a mixed solution of0.8 g of azobisdimethylvaleronitrile and 18 g of methylethylketone wasadded in drops to the flask over 0.5 hour and allowed to mature at 65°C. for one hour. Zero point eight grams (0.8 g) ofazobisdimethylvaleronitrile was added and allowed to mature for anotherone hour. After the reaction completed, 364 g of methylethylketone wasadded to the flask to obtain 800 g of a polymer solution having aconcentration of 50% by mass. Then, part of the polymer solution wasdried and the mass average molecular mass was measured by gel permeationchromatography (standard: polystyrene, solvent: tetrahydrofuran). Themass average molecular mass found was 15,000.

Twenty-eight grams (28 g) of the obtained polymer solution, 26 g ofcopper phthalocyanine pigment, 13.6 g of 1 mol/L aqueous potassiumhydroxide, 20 g of methylethylketone, and 30 g of deionized water werewell stirred and, then, kneaded with a triple roll mill (by NoritakeCo., Ltd., trade name: NR-84A) 20 times. The obtained paste wasintroduced in 200 g of deionized water and well stirred. Themethylethylketone and water were distilled away using an evaporator toobtain 160 g of a blue polymer fine-particles dispersion having a solidcontent of 20.0% by mass.

The obtained polymer fine-particles had a volume average particlediameter (D50%) of 93 nm as measured by a particle diameter distributionmeasuring device (Microtrac UPA, by Nikkiso Co., Ltd.).

Preparation Example 2

—Preparation of Dimethylquinacridone Pigment-Containing PolymerFine-Particles Dispersion—

A purplish red polymer fine-particles dispersion was obtained in thesame manner as in Preparation Example 1 except that the copperphthalocyanine pigment was replaced with a pigment C.I. Pigment Red 122.

The obtained polymer fine-particles had a volume average particlediameter (D50%) of 127 nm as measured by a particle diameterdistribution measuring device (Microtrac UPA, by Nikkiso Co., Ltd.).

Preparation Example 3

—Preparation of Monoazo Yellow Pigment-Containing Polymer Fine-ParticlesDispersion—

A yellow polymer fine-particles dispersion was obtained in the samemanner as in Preparation Example 1 except that the copper phthalocyaninepigment was replaced with a pigment C.I. Pigment Yellow 74.

The obtained polymer fine-particles had a volume average particlediameter (D50%) of 76 nm as measured by a particle diameter distributionmeasuring device (Microtrac UPA, by Nikkiso Co., Ltd.).

Preparation Example 4

—Preparation of Carbon Black Dispersion—

Three hundred grams (300 g) of a commercially available pH2.5 acidiccarbon black (by Cabot Corporation, trade name: Monak 1300) was wellmixed with 1,000 ml of water. Then, 450 g of sodium hypochlorite(effective chlorine concentration 12%) was added in drops and stirred at100° C. to 105° C. for eight hours. Then, 100 g of sodium hypochlorite(effective chlorine concentration 12%) was further added to the solutionand dispersed for three hours in a horizontal dispersing machine.

The obtained slurry was diluted 10-fold with water and the pH wasadjusted with lithium hydroxide. After demineralized and concentrated toa conductivity of 0.2 mS/cm by ultra-filtration membrane, a carbon blackdispersion having a pigment concentration of 15% by mass was obtained.Larger particles were removed by centrifuge and the carbon blackdispersion was further filtered by a nylon filter having an average porediameter of 1 μm to obtain a carbon black dispersion.

The obtained polymer fine-particles had a volume average particlediameter (D50%) of 95 nm as measured by a particle diameter distributionmeasuring device (Microtrac UPA, by Nikkiso Co., Ltd.).

Preparation Example 5

—Preparation of Carbon Black Polymer Fine-Particles Dispersion—

A black polymer fine-particles dispersion was obtained in the samemanner as in Preparation Example 1 except that the copper phthalocyaninepigment was replaced with carbon black (by Degussa FW100).

The obtained polymer fine-particles had a volume average particlediameter (D50%) of 104 nm as measured by a particle diameterdistribution measuring device (Microtrac UPA, by Nikkiso Co., Ltd.).

Preparation Example 6

—Preparation of Diazo Compound-Treated Carbon Black Dispersion—

One hundred grams (10 g) of carbon black having a surface area of 230m²/g and a DBP oil absorption rate of 70 ml/100 g, 34g ofp-amino-N-benzoic acid, and 750 g of water were mixed and dispersed. 16g of nitric acid was added in drops and stirred at 70° C. Five minutesafter, a solution of 11 g of sodium nitrite in 50 g of water was addedand stirred for another one hour. The obtained slurry was diluted10-fold with water and centrifuged to remove larger particles, followingwhich the pH was adjusted with diethanolamine to pH 8 to pH 9. Afterdemineralization and concentrated by an ultra-filtration membrane, acarbon black dispersion having a pigment concentration of 15% by masswas obtained. The carbon black dispersion was further filtered by apolypropylene filter having an average pore diameter of 0.5 cm to obtaina carbon black dispersion.

The obtained carbon black dispersion had a volume average particlediameter (D50%) of 99 nm as measured by a particle diameter distributionmeasuring device (Microtrac UPA, by Nikkiso Co., Ltd.).

Preparation Example 7

—Preparation of Sulfonating Agent-Treated Carbon Black Dispersion—

One-hundred fifty grams (150 g) of a commercially available carbon blackpigment (by Degussa “Printex #85”) was well mixed in 400 ml ofsulfofuran and finely dispersed by a bead mill. Fifteen grams (15 g) ofamidosulfuric acid was added and stirred at 140° C. to 150° C. for 10hours. The obtained slurry was introduced in 1,000 ml of deionized waterand centrifuged at 12,000 rpm to obtain a surface-treated carbon blackwet cake. The obtained carbon black wet cake was again dispersed in2,000 ml of deionized water and the pH was adjusted with lithiumhydroxide. After demineralized and concentrated by ultra-filtrationmembrane, a carbon black dispersion having a pigment concentration of10% by mass was obtained. The carbon black dispersion was furtherfiltered by a nylon filter having an average pore diameter of 1 μm toobtain a carbon black dispersion.

The obtained carbon black dispersion had a volume average particlediameter (D50%) of 80 nm as measured by a particle diameter distributionmeasuring device (Microtrac UPA, by Nikkiso Co., Ltd.).

Preparation Example 8

—Preparation of Silicone-Modified Acrylic Resin Fine-Particles—

First, for preparing a resin solution, the inside of a 1 L flaskequipped with a mechanical stirrer, a thermometer, a nitrogen gas inlettube, a reflux tube, and a dropping funnel was sufficiently purged withnitrogen gas. Then, 10 g of Aquaron RN-20 (by Dai-ichi Kogyo Seiyaku,Co., Ltd.), 1 g of potassium persulfate, and 286 g of purified waterwere introduced and heated to 65° C. A mixed solution of 150 g of methylmethacrylate, 100 g of 2-ethylhexyl acrylate, 20 g of acrylic acid, 20 gof vinyltriethoxysilane, 10 g of Aquaron RN-20, 4 g of potassiumpersulfate, and 398.3 g of purified water was added in drops to theflask over 2.5 hours. After allowed to mature at 80° C. for three hours,the flask was cooled to approximately 35° C. over one hour by runningwater approximately at 20° C. outside the flask. The pH was adjustedwith potassium hydroxide to pH 7 to pH 8 to obtain 305 g ofsilicone-modified acrylic resin fine-particles.

The obtained resin fine-particles had a volume average particle diameter(D50%) of 130 nm as measured by a particle diameter distributionmeasuring device (Microtrac UPA, by Nikkiso Co., Ltd.).

The minimum film forming temperature (MFT) of the obtained resinfine-particles was measured according to JIS K 6828 using a temperaturegradient heat plate minimum film forming temperature measuring device.Specifically, in the temperature gradient heat plate minimum filmforming temperature measuring device, a temperature range suitable forthe sample to be measured was assumed so that the minimum film formingtemperature was observed at the center of the heat plate. The highertemperatures and the lower temperature were determined in the mannerthat the difference between the lowest and highest temperatures fell ina range between 20° C. and 40° C. The sample was quickly applied by anapplicator from the higher to lower temperature side. The lowesttemperature at which a continuous uniform film with no cracks was formedwas read as the minimum film forming temperature. The minimum filmforming temperature obtained was 0° C.

Preparation Example 9

—Preparation of Silicone-Modified Acrylic Resin Fine-Particles—

First, for preparing a resin solution, the inside of a 1 L flaskequipped with a mechanical stirrer, a thermometer, a nitrogen gas inlettube, a reflux tube, and a dropping funnel was sufficiently purged withnitrogen gas. Then, 10 g of Aquaron RN-20 (by Dai-ichi Kogyo Seiyaku,Co., Ltd.), 1 g of potassium persulfate, and 286 g of purified waterwere introduced and heated to 65° C. A mixed solution of 150 g of methylmethacrylate, 100 g of 2-ethylhexyl acrylate, 20 g of acrylic acid, 40 gof hexyltrimethoxysilane, 10 g of Aquaron RN-20, 4 g of potassiumpersulfate, and 398.3 g of purified water was added in drops to theflask over 3 hours. After allowed to mature at 80° C. for three hours,the flask was cooled to approximately 35° C. over one hour by runningwater approximately at 20° C. outside the flask. The pH was adjustedwith potassium hydroxide to pH 7 to pH 8 to obtain 318 g ofsilicone-modified acrylic resin fine-particles.

The obtained resin fine-particles had a volume average particle diameter(D50%) of 148 nm as measured by a particle size distribution measuringdevice (Microtrac UPA, by Nikkiso Co., Ltd.).

The minimum film forming temperature (MFT) of the obtained resinfine-particles was measured according to JIS K 6828 using a temperaturegradient heat plate minimum film forming temperature measuring device.Specifically, in the temperature gradient heat plate minimum filmforming temperature measuring device, a temperature range suitable forthe sample to be measured was assumed so that the minimum film formingtemperature was observed at the center of the heat plate. The highertemperatures and the lower temperature were determined in the mannerthat the difference between the lowest and highest temperatures fell ina range between 20° C. and 40° C. The sample was quickly applied by anapplicator from the higher to lower temperature side. The lowesttemperature at which a continuous uniform film with no cracks was formedwas read as the minimum film forming temperature. The minimum filmforming temperature obtained was 0° C.

Preparation Example 10

First, for preparing a resin solution, the inside of a 1 L flaskequipped with a mechanical stirrer, a thermometer, a nitrogen gas inlettube, a reflux tube, and a dropping funnel was sufficiently purged withnitrogen gas. Then, 100 g of purified water, 3 g of sodiumdodecylbenzenesulfonate, and 1 g of polyethylene glycol nonylphenyletherwere introduced, 1 g of ammonium persulfate and 0.2 g of sodiumhydrogensulfite were added, and heated to 60° C. Then, 30 g of butylacrylate, 40 g of methyl methacrylate, 19 g of butyl methacrylate, 10 gof vinylsilanetriolpotassium salt, and 1 g of3-methacryloxypropylmethyldimethoxysilane were added in drops to theflask over three hours. Meanwhile, the pH of the polymerization solutionwas adjusted with aqueous ammonium to pH 7 to obtain 95 g ofsilicone-modified acrylic resin fine-particles.

The obtained resin fine-particles had a volume average particle diameter(D50%) of 160 nm as measured by a particle diameter distributionmeasuring device (Microtrac UPA, by Nikkiso Co., Ltd.).

Using the polymer fine-particles dispersion, carbon black dispersion,and resin fine-particles obtained in Preparation Examples 1 to 10, inkwas produced as follows.

Production Example 1

—Production of Cyan Pigment Ink—

An ink composition having the following composition was produced and,then, filtered by a membrane filter with an average pore diameter 0.8 μmto prepare the ink of Production Example 1.

<Ink Composition>

-   -   a copper phthalocyanine pigment-containing polymer        fine-particles dispersion of Preparation Example 1 . . . 20.0%        by mass;    -   1,3-butanediol . . . 23.0% by mass;    -   glycerin . . . 8.0% by mass;    -   2-ethyl-1,3-hexanediol . . . 2.0% by mass;    -   fluorochemical surfactant having the following Structural        Formula (1) . . . 1.0% by mass;

where, n=4, m=21, p=4, and Rf=CF₂CF₃;

-   -   Proxel LV (by Abesia Co., Ltd.) . . . 0.2% by mass; and    -   deionized water to be 100% by mass.

Production Example 2

—Production of Magenta Pigment Ink—

An ink composition having the following composition was produced and,then, filtered by a membrane filter with an average pore diameter 0.8 μmto prepare the ink of Production Example 2.

<Ink Composition>

-   -   dimethylquinacridone pigment-containing polymer fine-particles        dispersion of Preparation Example 2 . . . 20.0% by mass;    -   1,3-butanediol . . . 22.5% by mass;    -   glycerin . . . 9.0% by mass;    -   2-ethyl-1,3-hexanediol . . . 2.0% by mass;    -   fluorochemical surfactant having the following Structural        Formula (1) . . . 1.0% by mass;

where, n=4, m=21, p=4, and Rf=CF₂CF₃;

-   -   Proxel LV (by Abesia Co., Ltd.) . . . 0.2% by mass; and    -   deionized water to be 100% by mass.

Production Example 3

—Production of Yellow Pigment Ink—

An ink composition having the following composition was produced and,then, filtered by a membrane filter with an average pore diameter 0.8 μmto prepare the ink of Production Example 3.

-   -   <Ink composition> monoazo yellow pigment-containing polymer        fine-particles dispersion of Preparation Example 3 . . . 20.0%        by mass;    -   1,6-hexanediol . . . 24.5% by mass;    -   glycerin . . . 8.0% by mass;    -   2-ethyl-1,3-hexanediol . . . 2.0% by mass;    -   fluorochemical surfactant having the following Structural        Formula (1) . . . 0.5% by mass;

where, n=4, m=21, p=4, and Rf=CF₂CF₃;

-   -   Proxel LV (by Abesia Co., Ltd.) . . . 0.2% by mass; and    -   deionized water to be 100% by mass.

Production Example 4

—Production of Black Pigment Ink—

An ink composition having the following composition was produced and,then, filtered by a membrane filter with an average pore diameter 0.8 μmto prepare the ink of Production Example 4.

-   -   <Ink composition> carbon black dispersion of Preparation Example        7 . . . 20.0% by mass;    -   1,5-pentanediol . . . 22.5% by mass;    -   glycerin . . . 7.5% by mass;    -   2-pyrrolidone . . . 2.0% by mass;    -   a 2-ethyl-1,3-hexanediol . . . 2.0% by mass;    -   a compound having the following formula . . . 1.0% by mass;        R—(OCH₂CH₂)_(n)OH

where R: C₁₂H₂₃ (that may be branched), n=9;

-   -   fluorochemical surfactant having the following Structural        Formula (1) . . . 0.1% by mass;    -   where, n=4, m=21, p=4, and Rf=CF₂CF₃; Proxel LV (by Abesia Co.,        Ltd.). 0.2% by mass; and    -   a deionized water to be 100% by mass.

Production Example 5

—Production of Cyan Pigment Ink—

An ink composition having the following composition was produced and,then, filtered by a membrane filter with an average pore diameter 0.8 μmto prepare the ink of Production Example 5.

<Ink Composition>

-   -   copper phthalocyanine pigment-containing polymer fine-particles        dispersion of Preparation Example 1 . . . 20.0% by mass;    -   3-methyl-1,3-butanediol . . . 10.0% by mass;    -   hexylene glycole . . . 4.0% by mass;    -   glycerin . . . 8% by mass;    -   2-ethyl-1,3-hexanediol . . . 2.0% by mass;    -   fluorochemical surfactant having the following Structural        Formula (1) . . . 0.5% by mass;

where, n=4, m=21, p=4, and Rf=CF₂CF₃;

-   -   Proxel LV (by Abesia Co., Ltd.) . . . 0.2% by mass; and    -   deionized water to be 100% by mass.

Production Example 6

—Production of Magenta Pigment Ink—

An ink composition having the following composition was produced and,then, filtered by a membrane filter with an average pore diameter 0.8 μmto prepare the ink of Production Example 6.

<Ink Composition>

-   -   dimethylquinacridone pigment-containing polymer fine-particles        dispersion of Preparation Example 2 . . . 20.0% by mass;    -   3-methyl-1,3-butanediol . . . 11.5% by mass;    -   ethylene glycol . . . 5.0% by mass;    -   glycerin . . . 7.5% by mass;    -   2-ethyl-1,3-hexanediol . . . 2.0% by mass;    -   fluorochemical surfactant having the following Structural        Formula . . . 0.5% by mass;

where, q=6, and Rf=CF₂CF₃;

-   -   Proxel LV (by Abesia Co., Ltd.) . . . 0.2% by mass; and    -   deionized water to be 100% by mass.

Preparation Example 7

—Preparation of Yellow Pigment Ink—

An ink composition having the following composition was produced and,then, filtered by a membrane filter with an average pore diameter 0.8 μmto prepare the ink of Production Example 7.

<Ink Composition>

-   -   C.I. Acid Yellow 23 . . . 4.0% by mass;    -   3-methyl-1,3-butanediol . . . 20.0% by mass;    -   1,3-butanediol . . . 8.5% by mass;    -   glycerin . . . 7.5% by mass;    -   2-ethyl-1,3-hexanediol . . . 2.0% by mass;    -   fluorochemical surfactant having the following Structural        Formula . . . 0.5% by mass;

where, q=6, and Rf=CF₂CF₃;

-   -   Proxel LV (by Abesia Co., Ltd.) . . . 0.2% by mass; and    -   deionized water to be 100% by mass.

Production Example 8

—Production of Black Pigment Ink—

An ink composition having the following composition was produced and,then, filtered by a membrane filter with an average pore diameter 0.8 μmto prepare the ink of Production Example 8.

<Ink Composition>

-   -   carbon black polymer fine-particles dispersion of Preparation        Example 5 . . . 5.0% by mass;    -   2-methyl-2,4-pentanediol . . . 11.5% by mass;    -   3-methyl-1,3-butanediol . . . 13.0% by mass;    -   glycerin . . . 7.5% by mass;    -   2-pyrrolidone . . . 2.0% by mass;    -   Unisafe A-LY (by NOF Corporation, amphoteric surfactant) . . .        2.0% by mass;    -   fluorochemical surfactant having the following Structural        Formula . . . 0.5% by mass;

where, q=6, and Rf=CF₃;

-   -   2,2,4-trimethyl-1,3-pentanediol . . . 2.0% by mass;    -   Proxel LV (by Abesia Co., Ltd.) . . . 0.2% by mass; and    -   deionized water to be 100% by mass.

Production Example 9

—Production of Cyan Pigment Ink—

An ink composition having the following composition was produced and,then, filtered by a membrane filter with an average pore diameter 0.8 μmto prepare the ink of Production Example 9.

<Ink Composition>

-   -   copper phthalocyanine pigment-containing polymer fine-particles        dispersion of Preparation Example 1 . . . 20.0% by mass;    -   3-methyl-1,5-pentanediol . . . 10.5% by mass.    -   3-methyl-1,3-butanediol . . . 13.0% by mass.    -   glycerin . . . 8.0% by mass;    -   2,2,4-trimethyl-1,3-pentanediol . . . 2.0% by mass.    -   Unisafe A-LM (by NOF Corporation, amphoteric surfactant) . . .        2.0% by mass;    -   fluorochemical surfactant having the following Structural        Formula . . . 0.5% by mass;

where, q=6, and Rf=CF₃;

-   -   Proxel LV (by Abesia Co., Ltd.) . . . 0.2% by mass; and    -   deionized water to be 100% by mass.

Production Example 10

—Production of Magenta Pigment Ink—

An ink composition having the following composition was produced and,then, filtered by a membrane filter with an average pore diameter 0.8 μmto prepare the ink of Production Example 10.

<Ink Composition>

-   -   dimethylquinacridone pigment-containing polymer fine-particles        dispersion of Preparation Example 2 . . . 20.0% by mass;    -   3-methyl-1,5-pentanediol . . . 5.0% by mass;    -   3-methyl-1,3-butanediol . . . 5.0% by mass;    -   glycerin . . . 10.0% by mass;    -   2,2,4-trimethyl-1,3-pentanediol . . . 2.0% by mass;    -   fluorochemical surfactant having the following Structural        Formula (1) . . . 0.1% by mass;

where, n=4, m=21, p=4, and Rf=CF₂CF₃;

-   -   ECTD-3NEX (by Nikko Chemicals Co., Ltd., anionic surfactant) . .        . 1.0% by mass;    -   Proxel LV (by Abesia Co., Ltd.) . . . 0.2% by mass; and    -   deionized water to be 100% by mass.

Production Example 11

—Preparation of Yellow Pigment Ink—

An ink composition having the following composition was produced and,then, filtered by a membrane filter with an average pore diameter 0.8 μmto prepare the ink of Production Example 11.

<Ink Composition>

-   -   monoazo yellow pigment-containing polymer fine-particles        dispersion of Preparation Example 3 . . . 20.0% by mass;    -   3-methyl-1,5-pentanediol . . . 12.5% by mass;    -   3-methyl-1,3-butanediol . . . 15.0% by mass;    -   glycerin . . . 7.0% by mass;    -   2,2,4-trimethyl-1,3-pentanediol . . . 2.0% by mass;    -   fluorochemical surfactant having the following Structural        Formula (1) . . . 0.1% by mass;

where, n=4, m=21, p=4, and Rf=CF₂CF₃;

-   -   Proxel LV (by Abesia Co., Ltd.) . . . 0.2% by mass; and    -   deionized water to be 100% by mass.

Production Example 12

—Production of Black Pigment Ink—

An ink composition having the following composition was produced and,then, filtered by a membrane filter with an average pore diameter 0.8 μmto prepare the ink of Production Example 12.

<Ink Composition>

-   -   carbon black dispersion of Preparation Example 6 . . . 20.0% by        mass;    -   3-methyl-1,3-butanediol . . . 12.5% by mass;    -   glycerin . . . 7.5% by mass;    -   2-pyrrolidone . . . 2.0% by mass;    -   2-ethyl-1,3-hexanediol . . . 2.0% by mass;    -   compound having the following formula . . . 2.0% by mass;        R—(OCH₂CH₂)_(n)OH

where R: C₁₂H₂₃ (that may be branched), n=9;

-   -   fluorochemical surfactant having the following Structural        Formula (1) . . . 0.1% by mass;    -   where, n=4, m=21, p=4, and Rf=CF₂CF₃;    -   Proxel LV (by Abesia Co., Ltd.) . . . 0.2% by mass; and

deionized water to be 100% by mass.

Production Example 13

—Production of Black Pigment Ink—

An ink composition having the following composition was produced and,then, filtered by a membrane filter with an average pore diameter 0.8 μmto prepare the ink of Production Example 13.

<Ink Composition>

-   -   carbon black dispersion of Preparation Example 5 . . . 20.0% by        mass;    -   3-methyl-1,3-butanediol . . . 22.5% by mass;    -   glycerin . . . 7.5% by mass;    -   2-pyrrolidone . . . 2.0% by mass;    -   2-ethyl-1,3-hexanediol . . . 2.0% by mass;    -   fluorochemical surfactant having the following Structural        Formula (1) . . . 0.5% by mass;

where, n=4, m=21, p=4, and Rf=CF₂CF₃;

-   -   Proxel LV (by Abesia Co., Ltd.) . . . 0.2% by mass; and    -   deionized water to be 100% by mass.

Production Example 14

—Production of Black Pigment Ink—

An ink composition having the following composition was produced and,then, filtered by a membrane filter with an average pore diameter 0.8 μmto prepare the ink of Production Example 14.

<Ink Composition>

-   -   carbon black dispersion of Preparation Example 4 . . . 20.0% by        mass;    -   3-methyl-1,3-butanediol . . . 17.5% by mass;    -   glycerin . . . 5.5% by mass;    -   2-pyrrolidone . . . 2.0% by mass;    -   2-ethyl-1,3-hexanediol . . . 2.0% by mass;    -   fluorochemical surfactant having the following Structural        Formula (1) . . . 0.1% by mass;

where, n=4, m=21, p=4, and Rf=CF₂CF₃;

-   -   Proxel LV (by Abesia Co., Ltd.) . . . 0.2% by mass; and    -   deionized water to be 100% by mass.

Production Example 15

—Production of Cyan Pigment Ink—

An ink composition having the following composition was produced and,then, filtered by a membrane filter with an average pore diameter 0.8 μmto prepare the ink of Production Example 15.

<Ink Composition>

-   -   monoazo yellow pigment-containing polymer fine-particles        dispersion of Preparation Example 3 . . . 20.0% by mass;    -   3-methyl-1,5-pentanediol . . . 12.5% by mass;    -   3-methyl-1,3-butanediol . . . 15.0% by mass;    -   glycerin . . . 7.0% by mass;    -   2,2,4-trimethyl-1,3-pentanediol . . . 2.0% by mass;    -   fluorochemical surfactant having the following Structural        Formula (1) . . . 0.1% by mass;

where, n=4, m=21, p=4, and Rf=C₄F₉;

-   -   Proxel LV (by Abesia Co., Ltd.) . . . 0.2% by mass; and    -   deionized water to be 100% by mass.

Production Example 16

—Production of Cyan Pigment Ink—

An ink composition having the following composition was produced and,then, filtered by a membrane filter with an average pore diameter 0.8 μmto prepare the ink of Production Example 16.

<Ink Composition>

-   -   copper phthalocyanine pigment-containing polymer fine-particles        dispersion of Preparation Example 1 . . . 20.0% by mass;    -   1,3-butanediol . . . 23.0% by mass.    -   glycerin . . . 8.0% by mass;    -   2-ethyl-1,3-hexanediol . . . 2.0% by mass;    -   fluorochemical surfactant having the following Structural        Formula (3-1) . . . 1.0% by mass;

where, q=6, and Rf=CF₂CF₃;

-   -   Proxel LV (by Abesia Co., Ltd.) . . . 0.2% by mass; and    -   deionized water to be 100% by mass.

Production Example 17

—Production of Magenta Pigment Ink—

An ink composition having the following composition was produced and,then, filtered by a membrane filter with an average pore diameter 0.8 μmto prepare the ink of Production Example 17.

<Ink Composition>

-   -   dimethylquinacridone pigment-containing polymer fine-particles        dispersion of Preparation Example 2 . . . 20.0% by mass;    -   3-methyl-1,3-butanediol . . . 22.5% by mass;    -   glycerin . . . 9.0% by mass;    -   2-ethyl-1,3-hexanediol . . . 2.0% by mass;    -   fluorochemical surfactant having the following Structural        Formula (3-1) . . . 1.0% by mass;

where, q=6, and Rf=CF₃;

-   -   Proxel LV (by Abesia Co., Ltd.) . . . 0.2% by mass; and    -   deionized water to be 100% by mass.

Production Example 18

—Production of Yellow Pigment Ink—

An ink composition having the following composition was produced and,then, filtered by a membrane filter with an average pore diameter 0.8 μmto prepare the ink of Production Example 18.

<Ink Composition>

-   -   monoazo yellow pigment-containing polymer fine-particles        dispersion of Preparation Example 3 . . . 20.0% by mass;    -   1,6-hexane-diol . . . 24.5% by mass;    -   glycerin . . . 8.0% by mass;    -   2-ethyl-1,3-hexanediol . . . 2.0% by mass;    -   fluorochemical surfactant having the following Structural        Formula (3-1) . . . 0.5% by mass;

where, q=6, and Rf=CF₃;

-   -   Proxel LV (by Abesia Co., Ltd.) . . . 0.2% by mass; and    -   deionized water to be 100% by mass.

Production Example 19

—Production of Black Pigment Ink—

An ink composition having the following composition was produced and,then, filtered by a membrane filter with an average pore diameter 0.8 μmto prepare the ink of Production Example 19.

<Ink Composition>

-   -   carbon black dispersion of Preparation Example 7 . . . 20.0% by        mass;    -   1,5-pentanediol . . . 22.5% by mass;    -   glycerin . . . 7.5% by mass;    -   2-pyrrolidone . . . 2.0% by mass;    -   2-ethyl-1,3-hexanediol . . . 2.0% by mass;    -   compound having the following formula . . . 1.0% by mass;        R—(OCH₂CH₂)_(n)OH

where R: C₁₂H₂₃ (that may be branched), n=9;

-   -   fluorochemical surfactant having the following Structural        Formula (3-1) . . . 0.1% by mass;

where, q=4, and Rf=CF₃;

-   -   Proxel LV (by Abesia Co., Ltd.) . . . 0.2% by mass; and    -   deionized water to be 100% by mass.

Production Example 20

—Production of Cyan Pigment Ink—

An ink composition having the following composition was produced and,then, filtered by a membrane filter with an average pore diameter 0.8 μmto prepare the ink of Production Example 20.

<Ink Composition>

-   -   copper phthalocyanine pigment-containing polymer fine-particles        dispersion of Preparation Example 1 . . . 20.0% by mass;    -   3-methyl-1,3-butanediol . . . 10.0% by mass;    -   hexylene glycole . . . 4.0% by mass;    -   glycerin . . . 8.0% by mass;    -   2-ethyl-1,3-hexanediol . . . 2.0% by mass;    -   fluorochemical surfactant having the following Structural        Formula (3-1) . . . 0.5% by mass;

where, q=6, and Rf=CF₂CF₃;

-   -   Proxel LV (by Abesia Co., Ltd.) . . . 0.2% by mass;    -   fine-particles of Preparation Example 10 . . . 5.0% by mass; and    -   deionized water to be 100% by mass.

Production Example 21

—Production of Magenta Pigment Ink—

An ink composition having the following composition was produced and,then, filtered by a membrane filter with an average pore diameter 0.8 μmto prepare the ink of Production Example 21.

<Ink Composition>

-   -   dimethylquinacridone pigment-containing polymer fine-particles        dispersion of Preparation Example 2 . . . 20.0% by mass;    -   3-methyl-1,3-butanediol . . . 11.5% by mass;    -   ethylene glycol . . . 5.0% by mass;    -   glycerin . . . 7.5% by mass;    -   2-ethyl-1,3-hexanediol . . . 2.0% by mass;    -   fluorochemical surfactant having the following Structural        Formula (3-1) . . . 0.1% by mass;

where, q=6, and Rf=CF₂CF₃;

-   -   Proxel LV (by Abesia Co., Ltd.) . . . 0.2% by mass;    -   fine-particles of Preparation Example 9 . . . 5.0% by mass; and    -   deionized water to be 100% by mass.

Preparation Example 22

—Preparation of Yellow Pigment Ink—

An ink composition having the following composition was produced and,then, filtered by a membrane filter with an average pore diameter 0.8 μmto prepare the ink of Production Example 22.

<Ink Composition>

-   -   C.I. Acid Yellow 23 . . . 4.0% by mass;    -   3-methyl-1,3-butanediol . . . 20.0% by mass;    -   1,3-butanediol . . . 8.5% by mass;    -   glycerin . . . 7.5% by mass;    -   2-ethyl-1,3-hexanediol . . . 2.0% by mass;    -   fluorochemical surfactant having the following Structural        Formula (3-1) . . . 0.5% by mass;

where, q=6, and Rf=CF₂CF₃;

-   -   Proxel LV (by Abesia Co., Ltd.) . . . 0.2% by mass;    -   fine-particles of Preparation Example 8 . . . 5.0% by mass; and    -   a deionized water to be 100% by mass.

Production Example 23

—Production of Black Pigment Ink—

An ink composition having the following composition was produced and,then, filtered by a membrane filter with an average pore diameter 0.8 μmto prepare the ink of Production Example 23.

<Ink Composition>

-   -   carbon black dispersion of Preparation Example 5 . . . 5.0% by        mass;    -   2-methyl-2,4-pentanediol . . . 11.5% by mass;    -   3-methyl-1,3-butanediol . . . 13.0% by mass;    -   glycerin . . . 7.5% by mass;    -   2-pyrrolidone . . . 2.0% by mass;    -   Unisafe A-LY (by NOF Corporation, amphoteric surfactant) . . .        2.0% by mass;    -   fluorochemical surfactant having the following Structural        Formula (3-1) . . . 0.5% by mass;

where, q=6, and Rf=CF₂CF₃;

-   -   2,2,4-trimethyl-1,3-pentanediol . . . 2.0% by mass;    -   Proxel LV (by Abesia Co., Ltd.) . . . 0.2% by mass;    -   fine-particles of Preparation Example 10 . . . 5% by mass; and    -   deionized water to be 100% by mass.

Production Example 24

—Production of Cyan Pigment Ink—

An ink composition having the following composition was produced and,then, filtered by a membrane filter with an average pore diameter 0.8 μmto prepare the ink of Production Example 24.

<Ink Composition>

-   -   copper phthalocyanine pigment-containing polymer fine-particles        dispersion of Preparation Example 1 . . . 20.0% by mass;    -   3-methyl-1,5-pentanediol . . . 10.5% by mass;    -   3-methyl-1,3-butanediol . . . 13.0% by mass;    -   glycerin . . . 8.0% by mass;    -   2,2,4-trimethyl-1,3-pentanediol . . . 2.0% by mass;    -   Unisafe A-LM (by NOF Corporation, amphoteric surfactant) . . .        2.0% by mass;    -   fluorochemical surfactant having the following Structural        Formula (3) . . . 0.1% by mass;

where, X═N(CH₃)C₃H₇, Y═OSO₃, q=6, and Rf=CF₂CF₃;

-   -   Proxel LV (by Abesia Co., Ltd.) . . . 0.2% by mass;    -   fine-particles of Preparation Example 8 . . . 5.0% by mass; and    -   deionized water to be 100% by mass.

Production Example 25

—Production of Magenta Pigment Ink—

An ink composition having the following composition was produced and,then, filtered by a membrane filter with an average pore diameter 0.8 μmto prepare the ink of Production Example 25.

<Ink Composition>

dimethylquinacridone pigment-containing polymer fine-particlesdispersion of Preparation Example 2 . . . 20.0% by mass;

-   -   a 3-methyl-1,5-pentanediol . . . 5.0% by mass;    -   3-methyl-1,3-butanediol . . . 5.0% by mass;    -   glycerin . . . 10.0% by mass;    -   2,2,4-trimethyl-1,3-pentanediol . . . 2.0% by mass;    -   fluorochemical surfactant having the following Structural        Formula (3-1) . . . 1.0% by mass;

where, q=6, and Rf=CF₂CF₃;

-   -   ECTD-3NEX (by Nikko Chemicals Co., Ltd., anionic surfactant) . .        . 1.0% by mass;    -   Proxel LV (by Abesia Co., Ltd.) . . . 0.2% by mass; and    -   fine-particles of Preparation Example 10 . . . 5% by mass; and    -   deionized water to be 100% by mass.

Production Example 26

—Production of Yellow Pigment Ink—

An ink composition having the following composition was produced and,then, filtered by a membrane filter with an average pore diameter 0.8 μmto prepare the ink of Production Example 26.

<Ink Composition>

-   -   monoazo yellow pigment-containing polymer fine-particles        dispersion of Preparation Example 3 . . . 20.0% by mass;    -   3-methyl-1,3-butanediol . . . 15.0% by mass;    -   glycerin . . . 7.0% by mass;    -   2,2,4-trimethyl-1,3-pentanediol . . . 2.0% by mass;    -   fluorochemical surfactant having the following Structural        Formula (3-1) . . . 1.0% by mass;

where, q=6, and Rf=CF₃;

-   -   Proxel LV (by Abesia Co., Ltd.) . . . 0.2% by mass; and    -   fine-particles of Preparation Example 10 . . . 10.0% by mass;        and    -   deionized water to be 100% by mass.

Production Example 27

—Production of Black Pigment Ink—

An ink composition having the following composition was produced and,then, filtered by a membrane filter with an average pore diameter 0.8 μmto prepare the ink of Production Example 27.

<Ink Composition>

-   -   carbon black dispersion of Preparation Example 6 . . . 20.0% by        mass;    -   3-methyl-1,3-butanediol . . . 12.5% by mass;    -   glycerin . . . 7.5% by mass;    -   2-pyrrolidone . . . 2.0% by mass;    -   2-ethyl-1,3-hexanediol . . . 2.0% by mass;    -   fluorochemical surfactant having the following Structural        Formula (3-1) . . . 1.0% by mass;

where, q=6, and Rf=CF₃;

-   -   Proxel LV (by Abesia Co., Ltd.) . . . 0.2% by mass; and    -   fine-particles of Preparation Example 10 . . . 10% by mass; and    -   deionized water to be 100% by mass.

Production Example 28

—Production of Black Pigment Ink—

An ink composition having the following composition was produced and,then, filtered by a membrane filter with an average pore diameter 0.8 μmto prepare the ink of Production Example 28.

<Ink Composition>

-   -   carbon black dispersion of Preparation Example 5 . . . 20.0% by        mass;    -   3-methyl-1,3-butanediol . . . 22.5% by mass;    -   glycerin . . . 7.5% by mass;    -   2-pyrrolidone . . . 2.0% by mass;    -   2-ethyl-1,3-hexanediol . . . 2.0% by mass;    -   fluorochemical surfactant having the following Structural        Formula (3) . . . 0.1% by mass;

where, X═N(CH₃)C₃H₇, Y—OSO₃, q=6, and Rf=CF₂CF₃;

-   -   Proxel LV (by Abesia Co., Ltd.) . . . 0.2% by mass;    -   fine-particles of Preparation Example 10 . . . 4.0% by mass; and    -   deionized water to be 100% by mass.

Production Example 29

—Production of Black Pigment Ink—

An ink composition having the following composition was produced and,then, filtered by a membrane filter with an average pore diameter 0.8 μmto prepare the ink of Production Example 29.

<Ink Composition>

-   -   carbon black dispersion of Preparation Example 4 . . . 20.0% by        mass;    -   3-methyl-1,3-butanediol . . . 17.5% by mass;    -   glycerin . . . 5.5% by mass;    -   2-pyrrolidone . . . 2.0% by mass;    -   2-ethyl-1,3-hexanediol . . . 2.0% by mass;    -   fluorochemical surfactant having the following Structural        Formula (3-1) . . . 1.0% by mass;

where, q=6, and Rf=CF₃;

-   -   Proxel LV (by Abesia Co., Ltd.) . . . 0.2% by mass; and    -   deionized water to be 100% by mass.

Comparative Production Example 1

—Production of Cyan Pigment Ink—

The ink of Comparative Production Example 1 was prepared in the samemanner as in Production Example 1 except that the fluorochemicalsurfactant having the Structural Formula (1) was replaced with ECTD-3NEX(by Nikko Chemicals Co., Ltd., anionic surfactant).

Comparative Production Example 2

—Production of Magenta Pigment Ink—

The ink of Comparative Production Example 2 was prepared in the samemanner as in Production Example 2 except that the fluorochemicalsurfactant having the Structural Formula (1) was replaced with ECTD-6NEX(by Nikko Chemicals Co., Ltd., anionic surfactant).

Comparative Production Example 3

—Production of Yellow Pigment Ink—

The ink of Comparative Production Example 3 was prepared in the samemanner as in Production Example 3 except that the fluorochemicalsurfactant having the Structural Formula (1) was replaced with UnisafeA-LV (by NOF Corporation, amphoteric surfactant).

Comparative Production Example 4

—Production of Black Pigment Ink—

The ink of Comparative Production Example 4 was prepared in the samemanner as in Production Example 4 except that the fluorochemicalsurfactant having the Structural Formula (1) was replaced with NissanAnon BL-SF (by NOF Corporation, amphoteric surfactant).

Comparative Production Example 5

—Production of Cyan Pigment Ink—

The ink of Comparative Production Example 5 was prepared in the samemanner as in Production Example 5 except that the fluorochemicalsurfactant having the Structural Formula (1) was replaced with ECTD-3NEX(by Nikko Chemicals Co., Ltd., anionic surfactant).

Comparative Production Example 6

—Production of Magenta Pigment Ink—

The ink of Comparative Production Example 6 was prepared in the samemanner as in Production Example 6 except that the fluorochemicalsurfactant having the Structural Formula (2) was replaced with ECTD-3NEX(by Nikko Chemicals Co., Ltd., anionic surfactant).

Examples A-1 to A-17 and Comparative Examples A-1 to A-4

Using the inks of Production Examples 1 to 29 and Comparative ProductionExamples 1 to 6 in combinations shown in Table 1, ink sets of ExamplesA-1 to A-17 and Comparative Examples A-1 to A-4 were prepared in aconventional technique. TABLE 1 Ink Set Cyan Ink Yellow Ink Magenta InkBlack Ink Example A-1 Production Production Production ProductionExample 1 Example 3 Example 2 Example 4 Example A-2 ProductionProduction Production Production Example 5 Example 11 Example 6 Example8 Example A-3 Production Production Production Production Example 9Example 11 Example 10 Example 12 Example A-4 Production ProductionProduction Production Example 1 Example 11 Example 10 Example 13 ExampleA-5 Production Production Production Production Example 5 Example 3Example 2 Example 14 Example A-6 Production Production ProductionProduction Example 1 Example 3 Example 2 Example 8 Example A-7Production Production Production Production Example 5 Example 11 Example6 Example 4 Example A-8 Production Production Production ProductionExample 1 Example 3 Example 2 Example 12 Example A-9 ProductionProduction Production Production Example 5 Example 3 Example 10 Example4 Example A-10 Production Production Production Production Example 9Example 3 Example 2 Example 8 Example A-11 Production ProductionProduction Production Example 5 Example 7 Example 10 Example 4 ExampleA-12 Production Production Production Production Example 9 Example 15Example 2 Example 8 Example A-13 Production Production ProductionProduction Example 16 Example 22 Example 21 Example 27 Example A-14Production Production Production Production Example 24 Example 18Example 25 Example 28 Example A-15 Production Production ProductionProduction Example 16 Example 26 Example 17 Example 19 Example A-16Production Production Production Production Example 20 Example 26Example 21 Example 29 Example A-17 Production Production ProductionProduction Example 24 Example 22 Example 25 Example 23 Comp. Ex. A-1Comp. Production Comp. Production Comp. Production Comp. ProductionExample 1 Example 3 Example 2 Example 4 Comp. Ex. A-2 Comp. ProductionComp. Production Comp. Production Comp. Production Example 5 Example 3Example 6 Example 4 Comp. Ex. A-3 Comp. Production Comp. ProductionComp. Production Comp. Production Example 1 Example 3 Example 6 Example4 Comp. Ex. A-4 Comp. Production Comp. Production Comp. Production Comp.Production Example 5 Example 3 Example 2 Example 4<Printer Used>

Printing was conducted on the following regular paper using the inkjetprinter shown in FIGS. 3 to 5 (by Ricoh Company, Ltd., IPSiO G707).

<Paper Used for Printing>

The test print paper was My Paper (by NBS Ricoh Company, Ltd.).

<Evaluation 1. Color Image Evaluation—Color Development Evaluation(Solor Saturation)>

Printing was conducted on My Paper (by NBS Ricoh Company, Ltd.) usingthe inkjet printer shown in FIGS. 3 to 5 (by Ricoh Company, Ltd., IPSiOG707). The print pattern included 100% duty printing of yellow, magenta,and cyan color inks. The print conditions included a recording densityof 360 dpi and one-pass printing.

After drying, the yellow, magenta, and cyan solid color image parts weremeasured by a reflection color spectral colorimetry densitometer (byX-Rite K.K.) to obtain coordinates on the L*a*b* color system for thecolor difference indication defined by CIE (Commision International del'Eclairage). The color saturation C* expressed by the equationC*={(a*)²+(b*)²}^(1/2) was obtained for each color. Higher colorsaturation values C* indicate better color development, by which the inkis capable of forming a highly uniform solid image part. The results areshown in Table 2. TABLE 2 Color Saturation C* Yellow Ink Magenta InkCyan Ink Example A-1 80.09 61.42 51.07 Example A-2 82.24 60.43 51.35Example A-3 82.35 61.58 50.75 Example A-4 82.37 61.68 51.16 Example A-580.01 61.49 51.46 Example A-6 80.06 61.54 51.09 Example A-7 82.19 60.4951.39 Example A-8 80.99 61.39 51.13 Example A-9 80.07 61.63 51.42Example A-10 80.06 61.35 50.88 Example A-11 83.07 61.63 51.42 ExampleA-12 79.96 61.35 50.88 Example A-13 80.05 61.61 51.52 Example A-14 79.6561.72 51.11 Example A-15 81.07 61.62 51.67 Example A-16 80.98 61.5251.23 Example A-17 79.97 61.67 51.05 Comp. Ex. A-1 76.73 57.02 48.62Comp. Ex. A-2 76.68 58.22 49.11 Comp. Ex. A-3 76.61 58.14 48.57 Comp.Ex. A-4 76.60 57.04 49.23<Evaluation 2. Discharge Stability Evaluation in Intermittent Printing>

Printing was conducted on My Paper (by NBS Ricoh Company, Ltd.) usingthe inkjet printer shown in FIGS. 3 to 5 (by Ricoh Company, Ltd., IPSiOG707). The print pattern included a chart containing 5% print area in atotal area of the paper within the image region being printed at 100%duty in yellow, magenta, cyan, and black inks. The print conditionsincluded a recording density of 360 dpi and one-pass printing.

Evaluation 2 followed Evaluation 1 for each ink set of the aboveExamples and Comparative Examples.

In intermittent printing, the chart was continuously printed on 200sheets of paper and, then, the printing was paused for 20 minutes. Thisoperation was repeated 50 times. After a total of 1,000 printings, thechart was printed one more time and visually evaluated for the presenceof streaking, white spots, and disturbed jet according to the followingcriteria. The results are shown in Table 3.

[Evaluation Criteria]

A: no streaking, white spots, or disturbed jet in the solid parts;

B: slight streaking, white spots, or disturbed jet is observed in thesolid parts;

C: streaking, white spots, or disturbed jet is observed in the firstscan; and

D: streaking, white spots, or disturbed jet is observed throughout thesolid parts.

<Evaluation 3. Bleed Evaluation Between Color Ink and Black Ink>

Printing was conducted on My Paper (by NBS Ricoh Company, Ltd.) usingthe inkjet printer shown in FIGS. 3 to 5 (by Ricoh Company, Ltd., IPSiOG707). The print pattern included 100% duty printing in yellow ink.Then, black ink printing was conducted in the obtained yellow solidimage part. Bleed (running ink) between the yellow and black inks wasvisually evaluated according to the following criteria. The printconditions included a recording density of 360 dpi and one-passprinting.

[Evaluation Criteria]

A: no bleed is observed and clearly black letters appear;

B: slight bleed is observed and black letters have slightly running ink;and

C: Bleed occurs and it is difficult to recognize black letters. TABLE 3Discharge Stability Bleeding Example A-1 A A Example A-2 A A Example A-3A A Example A-4 A A Example A-5 A A Example A-6 A A Example A-7 A AExample A-8 A A Example A-9 A A Example A-10 A A Example A-11 A AExample A-12 A A Example A-13 A A Example A-14 A A Example A-15 A AExample A-16 A A Example A-17 A A Comp. Ex. A-1 C C Comp. Ex. A-2 D CComp. Ex. A-3 B B Comp. Ex. A-4 C C

Example B-1

—Preparation of Yellow Pigment Ink—

A yellow pigment was prepared by treating C.I. Pigment Yellow 128 at lowtemperature plasma to introduce a carboxylic acid group. This yellowpigment was dispersed in deionized water and de-mineralized andconcentrated by ultra-filtration membrane to obtain a yellow pigmentdispersion having a pigment concentration of 15% by mass.

The following ink composition was mixed and stirred and filtered by apolypropylene filter having an average pore diameter of 0.8 μm toprepare an ink.

<Ink Composition>

-   -   The above yellow pigment dispersion . . . 40 parts by mass;    -   diethylene glycol . . . 20 parts by mass;    -   glycerin . . . 10 parts by mass;    -   fluorochemical surfactant (FS-300, by DuPont Kabushiki Kaisha) .        . . 1.5 parts by mass;        CF₃CF₂(CF₂CF₂)_(j)—CH₂CH₂O(CH₂CH₂O)_(k)H

where, j is 6 to 8, k is 26 or more;

-   -   2-amino-2-methyl-1,3-propanediol . . . 0.6 parts by mass;    -   Proxel LV (by Abesia Co., Ltd.) . . . 0.2 parts by mass; and    -   deionized water . . . 28.7 parts by mass.

Example B-2

—Preparation of Magenta Pigment Ink—

A magenta pigment was prepared by treating C.I. Pigment Magenta 122 atlow temperature plasma to introduce a carboxylic acid group. Thismagenta pigment was dispersed in deionized water and de-mineralized andconcentrated by ultra-filtration membrane to obtain a magenta pigmentdispersion having a pigment concentration of 15% by mass.

The following ink composition was mixed and stirred and filtered by apolypropylene filter having an average pore diameter of 0.8 μm toprepare an ink.

<Ink Composition>

-   -   The above magenta pigment dispersion . . . 40 parts by mass;    -   diethylene glycol . . . 20 parts by mass;    -   glycerin . . . 10 parts by mass;    -   fluorochemical surfactant having the following Structural        formula . . . 1 part by mass;

where, n=4, m=21, p=4, and Rf=CF₂CF₃;

-   -   1-methylamino-2,3-propanediol . . . 0.4 parts by mass;    -   Proxel LV (by Abesia Co., Ltd.) . . . 0.5 parts by mass; and    -   deionized water . . . 28.1 parts by mass.

Example B-3

—Preparation of Cyen Polymer Fine-Particles Dispersion—

A copper phthalocyanine pigment-containing polymer fine-particlesdispersion was prepared with reference to Preparation Example 3 ofJapanese Patent Application Laid-Open (JP-A) No. 2001-139849.

First, for preparing a polymer solution, the inside of a 1 L flaskequipped with a mechanical stirrer, a thermometer, a nitrogen gas inlettube, a reflux tube, and a dropping funnel was sufficiently purged withnitrogen gas. Then, 11.2 g of styrene, 2.8 g of acrylic acid, 12.0 g oflaurylmethacrylate, 4.0 g of polyethylene glycol methacrylate, 4.0 g ofstyrene macromer (by To a Gosei Co., Ltd., trade name: AS-6), and 0.4 gof mercaptoethanol were introduced and heated to 65° C. A mixed solutionof 100.8 g of styrene, 25.2 g of acrylic acid, 108.0 g oflayrylmethacrylate, 36.0 g of polyethylene glycol methacrylate, 60.0 gof hydroxyethylmethacrylate, 36.0 g of styrene macromer (by To a GoseiCo., Ltd., trade name: AS-6), 3.6 g of mercaptoethanol, 2.4 g ofazobisdimethylvaleronitrile, and 18 g of methylethylketone was added indrops to the flask over 2.5 hours. After the dropping, a mixed solutionof 0.8 g of azobisdimethylvaleronitrile and 18 g of methylethylketonewas added in drops to the flask over 0.5 hour and allowed to mature at65° C. for one hour. 0.8 g of azobisdimethylvaleronitrile was added andallowed to mature for another one hour. After the reaction completed,364 g of methylethylketone was added to the flask to obtain 800 g of apolymer solution having a concentration of 50% by mass.

Twenty-eight grams (28 g) of the obtained polymer solution, 26 g ofcopper phthalocyanine pigment, 13.6 g of 1 mol/L aqueous potassiumhydroxide, 20 g of methylethylketone, and 30 g of deionized water werewell stirred and, then, kneaded with a triple roll mill (by NoritakeCompany, trade name: NR-84A) 20 times. The obtained paste was introducedin 200 g of deionized water and well stirred. The methylethylketone andwater were distilled away using an evaporator to obtain 160 g of a cyanpolymer fine-particles dispersion having a solid content of 20.0% bymass.

—Preparation of Cyan Pigment Ink—

Using the obtained cyan polymer fine-particle dispersion, the followingcomposition was mixed and stirred and filtered by a polypropylene filterhaving an average pore diameter of 0.8 μm to prepare an ink.

<Ink Composition>

-   -   The above cyan polymer fine-particle dispersion . . . 45 parts        by mass;    -   1,3-butanediol . . . 21 parts by mass;    -   glycerin . . . 8.0 parts by mass;    -   fluorochemical surfactant (FNS-100, by DuPont Kabushiki Kaisha)        . . . 1% by mass;        CF₃CF₂(CF₂CF₂)_(j)—CH₂CH₂—O—(CH₂CH₂O)_(k)H

where, j is 1 to 9, k is 0 to 25;

-   -   2-amino-2-methyl-1,3-propanediol . . . 0.8 parts by mass;    -   Proxel LV (by Abesia Co., Ltd.) . . . 0.5 parts by mass; and    -   deionized water . . . 21.7 parts by mass.

Example B-4

—Preparation of Cyan Pigment Ink—

The ink of Example B-4 was prepared in the same manner as in Example B-3except that 0.08 parts by mass of 2-amino-2-ethyl-1,3-propanediol and24.7 parts by mass of deionized water were used.

Example B-5

—Preparation of Cyan Pigment Ink—

The ink of Example B-5 was prepared in the same manner as in Example B-3except that 3.0 parts by mass of 2-amino-2-ethyl-1,3-propanediol and23.7 parts by mass of deionized water were used.

Comparative Example B-1

—Preparation of Yellow Pigment Ink—

The ink of Comparative Example B-1 was prepared in the same manner as inExample B-1 except that no 2-amino-2-ethyl-1,3-propanediol was used.

Comparative Example B-2

—Preparation of Yellow Pigment Ink=13

The ink of Comparative Example B-2 was prepared in the same manner as inExample B-1 except that 0.1 parts by mass of benzotriazole was used inplace of 0.6 parts by mass of 2-amino-2-ethyl-1,3-propanediol.

Comparative Example B-3

—Preparation of Magenta Pigment Ink—

The ink of Comparative Example B-3 was prepared in the same manner as inExample B-2 except that no 1-methylamino-2,3-propanediol were not used.

Comparative Example B-4

—Preparation of Magenta Pigment Ink—

The ink of Comparative Example B-4 was prepared in the same manner as inExample B-2 except that no fluorochemical surfactant was used.

Comparative Example B-5

—Preparation of Cyan Pigment Ink—

The ink of Comparative Example B-5 was prepared in the same manner as inExample B-3 except that no 2-amino-2-ethyl-1,3-propanedio was used.

Comparative Example B-6

—Preparation of Cyan Pigment Ink—

The ink of Comparative Example B-6 was prepared in the same manner as inExample B-3 except that no fluorochemical surfactant FSN-100 was used.

The obtained inks were evaluated for properties as follows. The resultsare shown in Table 4.

<Printer Used>

The inkjet printer shown in FIGS. 3 to 5 (by Ricoh Company, Ltd., IPSiOG707) was used.

A silicone resin (by Toray Dow Corning Silicone Co., Ltd, SR2316) wasapplied on the discharging surface of the inkjet printer nozzle headportion by spraying to a thickness of approximately 1.0 μm to form anink repellent layer. While the ink repellent layer was formed, thenozzle and nozzle plate back surface were masked with a water-solubleresin. After the silicone resin layer was applied, the water-solubleresin film used as a mask was peeled off.

<Color Development (Color Saturation)>

My Paper (by NBS Ricoh Company, Ltd.) was used as the evaluation paperfor each ink. The printing conditions included a printing density of 360dpi and one-pass printing. The print pattern included 100% dutyprinting.

After drying, the solid color image parts were measured by a reflectioncolor spectral colorimetry densitometer (by X-Rite K.K.) to obtaincoordinates on the L*a*b* color system for the color differenceindication defined by CIE (Commision International de l'Eclairage). Thecolor saturation C* was obtained for each color. Higher color saturationvalues C* indicate better color development. The color saturation C* isdefined by the following Equation 1:C*={(a*)²+(b*)²}^(1/2)  Equation 1<Evaluation of Discharge Stability after Continuous Printing>

A chart containing 5% print area in a total area of the paper within theimage region was printed in each ink at 100% duty, a recording densityof 360 dpi, and one-pass printing in 10-minute continuous operation.Then, the solid parts were visually evaluated for the presence ofstreaking, white spots, and disturbed jet according to the followingcriteria.

[Evaluation Criteria]

A: no streaking, white spots, or disturbed jet in the solid parts;

B: slight streaking, white spots, or disturbed jet is observed in thesolid parts;

C: streaking, white spots, or disturbed jet is observed in the firstscan; and

D: streaking, white spots, or disturbed jet is observed throughout thesolid parts.

<Evaluation of Discharge Stability>

The 10-minute continuous operation was conducted for each ink under thesame conditions as the discharge stability evaluation after continuousprinting. A moisture retention cap was placed with the ink remainingadhered to the head surface and the printer was allowed to stand at 50°C. and 60% RH for one month. Then, the printer was cleaned to recoverthe same condition as before the standing. Then, an intermittentprinting test was conducted under the following conditions to evaluatedischarge stability. The following print pattern chart was continuouslyprinted on 20 sheets of paper and, then, the printing was paused for 20minutes. This operation was repeated 50 times. After a total of 1000printings, the chart was printed one more time and visually evaluatedfor the presence of streaking, white spots, and disturbed jet accordingto the following criteria.

The print pattern chart containing 5% print area in a total area of thepaper within the image region was printed at 100% duty in each ink. Theprint conditions included a recording density of 360 dpi and one-passprinting.

[Evaluation Criteria]

A: no streaking, white spots, or disturbed jet in the solid parts;

B: slight streaking, white spots, or disturbed jet is observed in thesolid parts;

C: streaking, white spots, or disturbed jet is observed in the firstscan; and

D: streaking, white spots, or disturbed jet is observed throughout thesolid parts. TABLE 4 Color Discharge Discharge Stability developmentStability after standing Example B-1 82.4 (Y) A A Example B-2 61.1 (M) AB Example B-3 51.5 (C) A A Example B-4 51.5 (C) A B Example B-5 51.2 (C)B B Comp. Ex. B-1 82.4 (Y) B D Comp. Ex. B-2 82.3 (Y) B C Comp. Ex. B-361.0 (M) B D Comp. Ex. B-4 56.7 (M) B C Comp. Ex. B-5 51.5 (C) B D Comp.Ex. B-6 49.1 (C) B C* color development in parenthesis ( ) shows ink color.

From the results in Table 4, Examples B-1 to B-5 yielded excellent colordevelopment, discharge stability, and discharge stability after standingcompared with Comparative Example B-1 to B-6. Particularly excellentdischarge stability after standing was obtained. There was no siliconeresin eluting from the nozzle head ink repellent layer; therefore, noreduced or uneven ink repellency was observed. Consequently, dischargestability was not deteriorated during the intermittent printing.

INDUSTRIAL APPLICABILITY

The recording ink of the present invention achieves improved colordevelopment, highly stable discharge, and excellently uniform solidimage parts, thereby high quality images can be formed, and ispreferably used in the ink cartridge, ink record, inkjet recordingapparatus, and inkjet recording method.

The inkjet recording apparatus and inkjet recording method of thepresent invention are applicable to various recording in an inkjetrecording system. For example, the inkjet recording apparatus and inkjetrecording method of the present invention can be particularly preferablyapplied to inkjet recording printers, facsimiles, copy machines, andprinter/fax/copy complex machines.

1. A recording ink comprising: water, a water-soluble organic solvent, acolorant, and at least one fluorochemical surfactant selected from thefollowing Structural Formulae (1) to (3):

where, Rf is a fluorine-containing group; and m, n and p are integers inthe Structural Formula (1);

where, Rf is a fluorine-containing group; X is a cationic group; Y isanionic group and q is an integer in the Structural Formula (2); and

where, Rf is a fluorine-containing group; X is a cationic group; Y is ananionic group; and q is an integer in the Structural Formula (3).
 2. Therecording in according to claim 1, wherein Rf in the Structural Formulae(1) to (3) is a perfluoroalkyl group.
 3. The recording ink according toclaim 1, wherein the fluorochemical surfactant is at least one selectedfrom the following Structural Formulae (1-1) to (3-1):

where, Rf is CF₃ or CF₂CF; and n is 1 to 4, is 6 to 25, and p is 1 to 4;

where, Rf is CF₃ or CF₂CF₃; and q is 1 to 6; and

where, Rf is CF₃ or CF₂CF₃; and q is 1 to
 6. 4. The recording inkaccording to claim 1, wherein the content of at least one fluorochemicalsurfactant selected from the Structural Formulae (1) to (3) is 0.01% bymass to 10% by mass.
 5. The recording ink according to claim 1, whereinthe colorant is at least one of pigments, dyes, and coloringfine-particles.
 6. The recording ink according to claim 5, wherein thepigment comprises at least one hydrophilic group on the surface, and isat least one of water-dispersible and water-soluble in the absence ofdispersant.
 7. The recording ink according to claim 1, wherein thewater-soluble organic solvent is at least one selected from glycerin,ethylene glycol, diethylene glycol, triethylene glycol, propyleneglycol, dipropylene glycol, tripropylene glycol, 1,3-butanediol,2,3-butanediol, 1,4-butanediol, 3-methyl-1,3-butanediol,1,5-pentanediol, tetraethylene glycol, 1,6-hexanediol,2-methyl-2,4-pentanediol, polyethylene glycol, 1,2,4-butanetriol,1,2,6-hexanetriol, thiodiglycol, 2-pyrrolidone, N-methyl-2-pyrrolidoneand N-hydroxyethyl-2-pyrrolidone.
 8. The recording ink according toclaim 1, comprising at least one selected from cyan ink, magenta ink,yellow ink and black ink.
 9. An ink cartridge comprising a containercontaining a recording ink, wherein the recording ink comprises at leastwater, a water-soluble organic solvent, a colorant, and at least onefluorochemical surfactant selected from the following StructuralFormulae (1) to (3):

where, Rf is a fluorine-containing group and m, n, and p are integers inthe Structural Formula (1);

where, Rf is a fluorine-containing group; X is a cationic group; Y is ananionic group; and q is an integer in the Structural Formula (2); and

where, Rf is a fluorine-containing group; X is a cationic group; Y is ananionic group; and is q is an integer in the Structural Formula (3). 10.An inkjet recording apparatus comprising: an ink drops discharging unitconfigured to discharge a recording ink drop to form an image byapplying an impulse to a recording ink, wherein the recording inkcomprises at least water, a water-soluble organic solvent, a colorant,and at least one fluorochemical surfactant selected from the followingStructural Formulae (1) to (3):

where, Rf is a fluorine-containing group; and m, n, and p are integersin the Structural Formula (1);

where, Rf is a fluorine-containing group; X is a cationic group; Y is ananionic group; and q is an integer in the Structural Formula (2); and

where, Rf is a fluorine-containing group; X is a cationic group; Y is ananionic group; and q is an integer in the Structural Formula (3).
 11. Aninkjet recording apparatus comprising: an ink drops discharging unitconfigured to discharge a recording ink drop to form an image byapplying an impulse to a recording ink, wherein the ink dropsdischarging unit comprises a nozzle head portion having a siliconeresin-containing ink repellent layer on the in discharging surface, andwherein the ink used in the inkjet recording apparatus comprises atleast water, a colorant, a fluorochemical surfactant, and anaminopropanediol compound.
 12. The inkjet recording apparatus accordingto claim 11 wherein the aminopropanediol compound is2-amino-2-ethyl-1,3-propanediol.
 13. The inkjet recording apparatusaccording to claim 11, wherein the content of the aminopropanediolcompound in the ink is 0.01% by mass to 10% by mass.
 14. The inkjetrecording apparatus according to claim 11, wherein the fluorochemicalsurfactant is at least one selected from the following StructuralFormulae (A), (1), (2) and (3):CF₃CF₂(CF₂CF₂)_(j)—CH₂CH₂O(CH₂CH₂O)_(k)H  Structural Formula (A) where,j and k are integers in the Structural Formula (A);

where, Rf is a fluorine-containing group; and m, n, and p are integersStructural Formula (1);

where, Rf is a fluorine-containing group; X is a cationic group; Y is ananionic group and q is an integer in the Structural Formula (2); and

where, Rf is a fluorine-containing group; X is a cationic group; Y is ananionic group and q is an integer in the Structural Formula (3).
 15. Theinkjet recording apparatus according to claim 11, wherein the content ofthe fluorochemical surfactant in the ink is 0.05% by mass to 20% bymass.
 16. The inkjet recording apparatus according to claim 11, whereinthe colorant is at least one of pigments, dyes, and coloringfine-particles.
 17. The inkjet recording apparatus according to claim16, wherein the pigment comprises at least one hydrophilic group on thesurface, and is at least one of water-dispersible and water-soluble inthe absence of dispersant.
 18. The inkjet recording apparatus accordingto claim 10, wherein the impulse is at least one selected from heat,pressure, vibration, and light.
 19. An inkjet recording methodcomprising: discharging a recording ink drop to form an image byapplying an impulse to a recording ink, wherein the recording inkcomprises at least water, a water-soluble organic solvent, a colorant,and at least one fluorochemical surfactant selected from the followingStructural Formulae (1) to (3):

where, Rf is a fluorine-containing group; and m, n, and p are integersin the Structural Formula (1);

where, Rf is a fluorine-containing group; X is a cationic group; Y is ananionic group; and q is an integer in the Structural Formula (2); and

where, Rf is a fluorine-containing group; X is a cationic group; Y is ananionic group; and q is an integer in the Structural Formula (3).
 20. Aninkjet recording method comprising: discharging a recording ink drop toform an image by applying an impulse to a recording ink, wherein the inkdischarging is performed by using a nozzle head portion having asilicone resin-containing ink repellent layer on the ink dischargingsurface, and wherein the ink comprises at least water, a colorant, afluorochemical surfactant, and an aminopropanediol compound.
 21. Theinkjet recording method according to claim 20, wherein theaminopropanediol compound is 2-amino-2-ethyl-1,3-propanediol.
 22. Theinkjet recording method according to claim 20, wherein thefluorochemical surfactant is at least one selected from the followingStructural Formulae (A), (1), (2) and (3):CF₃CF₂(CF₂CF₂)_(j)—CH₂CH₂O(CH₂CH₂O)_(k)H  Structural Formula (A) where,j and k are integers in the Structural Formula (A);

where, Rf is a fluorine-containing group; and m, n, and p are integersin the Structural Formula (1);

where, Rf is a fluorine-containing group; X is a cationic group; Y is ananionic group; and q is an integer in the Structural Formula (2); and

where, Rf is a fluorine-containing group; X is a cationic group; Y is ananionic group; and q is an integer in the Structural Formula (3). 23.The inkjet recording method according to claim 19, wherein the impulseis at least one selected from heat, pressure, vibration, and light. 24.An in record comprising: an image formed using a recording ink, whereinthe recording ink comprises at least water, a water-soluble organicsolvent, a colorant, and at least one fluorochemical surfactant selectedfrom the following Structural Formulae (1) to (3):

where, Rf is a fluorine-containing group; and m, n, and p are integersin the Structural Formula (1);

where, Rf is a fluorine-containing group; X is a cationic group; Y is ananionic group; and q is an integer in the Structural Formula (2); and

where, Rf is a fluorine-containing group; X is a cationic group; Y is ananionic group; and q is an integer in the Structural Formula (3). 25.The inkjet recording apparatus according to claim 11, wherein theimpulse is at least one selected from heat pressure vibration and light.26. The ink et recording method according to claim 20 wherein theimpulse is at least one selected from heat, pressure, vibration, andlight.